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Л.Ф. Герасимова М.В. ЦЫГУЛЕВА

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Федеральное агентство по образованию Сибирская государственная

автомобильно-дорожная академия (СибАДИ)

Л.Ф. ГЕРАСИМОВА М.В. ЦЫГУЛЕВА

BRIDGES AND TUNNELS

учебное пособие

для студентов II курса

специальности «Мосты и транспортные тоннели»

Омск Издательство СибАДИ

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2006

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УДК 42:629.114 ББК 81.432.1:39.3

Рецензенты: Г.Г. Сёмкина, канд. филол. наук, доцент каф. английской фи-лологии ОмГУ; В.М. Левшунов, канд. техн. наук, доцент каф. механики и технологии строительства ОмГАУ

Работа одобрена редакционно-издательским советом академии в каче-

стве учебного пособия по английскому языку для студентов II курса спе-циальности «Мосты и транспортные тоннели»

Герасимова Л.Ф. Цыгулева М.В. Учебное пособие по английскому языку для студентов II курса специ-

альности «Мосты и транспортные тоннели». – Омск: Изд-во СибАДИ, 2006. – 232 с.

Учебное пособие содержит упражнения и тексты для студентов специ-

альности «Мосты и транспортные тоннели». Упражнения направлены на формирование у студентов речевых грамматических навыков на основе профессиональной лексики.

Л.Ф. Герасимова, М.В. Цыгулева, 2006

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PART I

Text 1 Read the text and say what new facts have you found out.

THE ANCIENT WORLD The first bridges were simply supported beams, such as flat stones or tree

trunks laid across a stream. For valleys and other wider channels – especially in East Asia and South America, where examples can still be found – ropes made of various grasses and vines tied together were hung in suspension for single-file crossing. Materials were free and abundant, and there were few labour costs, since the work was done by slaves, soldiers, or natives who used the bridges in daily life.

Some of the earliest known bridges are called clapper bridges (from Latin claperius, “pile of stones”). These bridges were built with long, thin slabs of stone to make a beam-type deck and with large rocks or blocklike piles of stones for piers. Postbridge in Devon, England, an early medieval clapper bridge, is an oft-visited example of this old type, which was common in much of the world, especially China.

Text 2 After reading the text write its short summary.

ROMAN ARCH BRIDGES The Romans began organized bridge building to help their military cam-

paigns. Engineers and skilled workmen formed guilds that were dispatched throughout the empire, and these guilds spread and exchanged building ideas and principles. The Romans also discovered natural cement, called pozzolana, which they used for piers in rivers.

Roman bridges are famous for using the circular arch form, which allowed for spans much longer than stone beams and for bridges of more permanence than wood. Where several arches were necessary for longer bridges, the building of strong piers was critical. This was a problem when the piers could not be built on rock, as in a wide river with a soft bed. To solve this dilemma, the Romans developed the cofferdam, a temporary enclosure made from wooden piles driven into the riverbed to make a sheath, which was often sealed with clay. Concrete was then poured into the water within the ring of piles. Although most surviving

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Roman bridges were built on rock, the Sant’Angelo Bridge in Rome stands on cofferdam foundations built in the Tiber River more than 1,800 years ago.

The Romans built many wooden bridges, but none has survived, and their reputation rests on their masonry bridges. One beautiful example is the bridge over the Tagus River at Alcántara, Spain. The arches, each spanning 98 feet, feature huge arch stones (voussoirs) weighing up to eight tons each. Typical of the best stone bridges, the voussoirs at Alcántara were so accurately shaped that no mortar was needed in the joints. This bridge has remained standing for nearly 2,000 years. Another surviving monument is the Pont du Gard aqueduct near Nîmes in southern France, completed in AD 14. This structure, almost 900 feet long, has three tiers of semicircular arches, with the top tier rising more than 150 feet above the river. The bottom piers form diamond-shaped points, called cut-waters, which offer less resistance to the flow of water.

Text 3 You have to make a report on Asian and European bridges. Use the infor-mation below for help.

ASIAN AND EUROPIAN CANTILEVER AND ARCH BRIDGES

In Asia, wooden cantilever bridges were popular. The basic design used piles driven into the riverbed and old boats filled with stones sunk between them to make cofferdam-like foundations. When the highest of the stone-filled boats reached above the low-water level, layers of logs were crisscrossed in such a way that, as they rose in height, they jutted farther out toward the adjacent piers. At the top, the Y-shaped, cantilevering piers were joined by long tree trunks. By crisscrossing the logs, the builders allowed water to pass through the piers, of-fering less resistance to floods than with a solid design. In this respect, these de-signs presaged some of the advantages of the early iron bridges.

In parts of China many bridges had to stand in the spongy silt of river val-leys. As these bridges were subject to an unpredictable assortment of tension and compression, the Chinese created a flexible masonry-arch bridge. Using thin, curved slabs of stone, the bridges yielded to considerable deformation be-fore failure.

In the Great Stone Bridge in Chao-chou, Hopeh Province, China, built by Li Ch’un between 589 and 618, the single span of 123 feet has a rise of only 23 feet from the abutments to the crown. This rise-to-span ratio of 1:5, much lower than the 1:2 ratio found in semicircular arches, produced a large thrust against the abutments. To reduce the weight, the builders made the spandrels (walls be-tween the supporting vault and deck) open. The Great Stone Bridge thus em-ployed a form rarely seen in Europe prior to the mid-18th century, and it antici-pated the reinforced-concrete designs of Robert Maillart in the 20th century.

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After the fall of the Roman Empire, progress in European bridge building slowed considerably until the Renaissance. Fine bridges sporadically appeared, however. Medieval bridges are particularly noted for the ogival, or pointed arch. With the pointed arch the tendency to sag at the crown is less dangerous, and there is less horizontal thrust at the abutments. Medieval bridges served many purposes. Chapels and shops were commonly built on them, and many were for-tified with towers and ramparts. Some featured a drawbridge, a medieval inno-vation. The most famous bridge of that age was Old London Bridge, begun in the late 12th century under the direction of a priest, Peter of Colechurch, and completed in 1209, four years after his death. London Bridge was designed to have 19 pointed arches, each with a 24-foot span and resting on piers 20 feet wide. There were obstructions encountered in building the cofferdams, however, so that the arch spans eventually varied from 15 to 34 feet. The uneven quality of construction resulted in a frequent need for repair, but the bridge held a large jumble of houses and shops and survived more than 600 years before being re-placed.

A more elegant bridge of the period was the Saint-Bénézet Bridge at Avi-gnon, France. Begun in 1177, part of it still stands today. Another medieval bridge of note is Monnow Bridge in Wales, which featured three separate ribs of stone under the arches. Rib construction reduced the quantity of material needed for the rest of the arch and lightened the load on the foundations.

Text 4 Work in two groups. After reading the text draw up a questionnaire for an-other group of students to find out how attentive these students are and how many facts they can remember.

THE RENAISSANCE AND AFTER

During the Renaissance, the Italian architect Andrea Palladio took the prin-ciple of the truss, which previously had been used for roof supports, and de-signed several successful wooden bridges with spans up to 100 feet. Longer bridges, however, were still made of stone. Another Italian designer, Bartolom-meo Ammannati, adapted the medieval ogival arch by concealing the angle at the crown and by starting the curves of the arches vertically in their springings from the piers. This elliptical shape of arch, in which the rise-to-span ratio was as low as 1:7, became known as basket-handled and has been adopted widely since. Ammannati’s elegant Santa Trinità Bridge (1569) in Florence, with two elliptical arches, carried pedestrians and later automobiles until it was destroyed during World War II; it was afterward rebuilt with many of the original materi-als recovered from the riverbed. Yet another Italian, Antonio da Ponte, designed the Rialto Bridge (1591) in Venice, an ornate arch made of two segments with a

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span of 89 feet and a rise of 21 feet. Antonio overcame the problem of soft, wet soil by having 6,000 timber piles driven straight down under each of the two abutments, upon which the masonry was placed in such a way that the bed joints of the stones were perpendicular to the line of thrust of the arch. This innovation of angling stone or concrete to the line of thrust has been continued into the pre-sent.

By the middle of the 18th century, bridge building in masonry reached its zenith. Jean-Rodolphe Perronet, builder of some of the finest bridges of his day, developed very flat arches supported on slender piers. His works included the Pont de Neuilly (1774), over the Seine, the Pont Sainte-Maxence (1785), over the Oise, and the beautiful Pont de la Concorde (1791), also over the Seine. In Great Britain, William Edwards built what many people consider the most beau-tiful arch bridge in the British Isles—the Pontypridd Bridge (1750), over the Taff in Wales, with a lofty span of 140 feet. In London the young Swiss engi-neer Charles Labelye, entrusted with the building of the first bridge at Westmin-ster, evolved a novel and ingenious method of sinking the foundations, employ-ing huge timber caissons that were filled with masonry after they had been floated into position for each pier. The 12 semicircular arches of portland stone, rising in a graceful camber over the river, set a high standard of engineering and architectural achievement for the next generation and stood for a hundred years.

Also in London, John Rennie, engaged by private enterprise in 1811, built the first Waterloo Bridge, whose level-topped masonry arches were described by the Italian sculptor Antonio Canova as “the noblest bridge in the world.” It was replaced by a modern bridge in 1937 – 45. Rennie subsequently designed the New London Bridge of multiple masonry arches. Completed in 1831, after Ren-nie’s death, it was subsequently widened and was finally replaced in the 1960s.

During the Industrial Revolution the timber and masonry tradition was eclipsed by the use of iron, which was stronger than stone and usually less costly. The first bridge built solely of iron spanned the River Severn near Coal-brookdale, England. Designed by Thomas Pritchard and built in 1779 by Abra-ham Darby, the Coalbrookdale Bridge, constructed of cast-iron pieces, is a ribbed arch whose nearly semicircular 100-foot span imitates stone construction by exploiting the strength of cast iron in compression. In 1795 the Severn region was wracked by disastrous floods, and the Coalbrookdale Bridge, lacking the wide flat surfaces of stone structures, allowed the floodwaters to pass through it. It was the only bridge in the region to survive – a fact noted by the Scottish en-gineer Thomas Telford, who then began to create a series of iron bridges that were judged to be technically the best of their time. The 1814 Craigellachie Bridge, over the River Spey in Scotland, is the oldest surviving metal bridge of Telford's. Its 150-foot arch has a flat, nearly parabolic profile made up of two curved arches connected by X-bracing. The roadway has a slight vertical curve and is supported by thin diagonal members that carry loads to the arch.

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The use of relatively economical wrought iron freed up the imaginations of designers, and one of the first results was Telford's use of chain suspension ca-bles to carry loads by tension. His eyebar cables consisted of wrought-iron bars of 20 to 30 feet with holes at each end. Each eye matched the eye on another bar, and the two were linked by iron pins. The first of these major chain-suspension bridges and the finest of its day was Telford's bridge over the Menai Strait in northwestern Wales. At the time of its completion in 1826, its 580-foot span was the world's longest. In 1893 its timber deck was replaced with a steel deck, and in 1940 steel chains replaced the corroded wrought-iron ones. The bridge is still in service today.

Text 5 Work in three groups. Render the article. Discuss all the variants and choose the best one.

THE FORTH BRIDGES In 1818 James Anderson designed a bridge of chains, which also came to

naught, a design which was later described as “so light a structure that it would hardly have been visible on a dull day, and after a heavy gale, it would no longer be seen on a clear day either”. In 1865 an Act of Parliament authorized the North British Railway and its engineer Thomas Bouch to construct a bridge across the Forth. He proposed a suspension bridge, bridging the Forth in twin spans of 1600 feet. Bouch was also the designer of the Tay Bridge, a project that culminated in him being knighted.

On the night of 28 December 1879, Sir Thomas Bouch received a telegram from Dundee at his house in Edinburgh. The Tay Bridge had been in operation for barely 19 months. The telegram Sir Thomas Bouch received that night read as follows: “Terrible accident on bridge one or more of girders blown down am not sure of the safety of the last down Edinbr train will advise further as soon as can be obtained”.

The Tay Bridge had collapsed in a hurricane and 75 railway passengers had been swept to their fate. The disaster put paid to Bouch’s Forth Bridge and he died a broken man a year later.

The Scottish poet McGonagle records the tragedy thus: Beautiful Railway Bridge of the Silvery Tay! Alas! I am very sorry to say That ninety lives have been taken away On the last Sabbath day of 1879, Which will be remembered for a very long time.

Bouch’s design for the Forth was abandoned and a new design by Benjamin Baker adopted in 1882. Not a suspension bridge this time, but the massive canti-

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lever structure now so familiar throughout the world. Baker conveyed the canti-lever principle to audiences nationwide. At the Royal Institution in 1887 he de-scribed it thus:

“Two men sitting on chairs extended their arms, and support the same by grasping sticks which are butted against the chairs. There are thus two complete piers, as represented in the outline drawing above their heads. The centre girder is represented by a stick suspended or slung from the two inner hands of the men, while the anchorage provided by the counterpose in the cantilever end piers is represented here by a pile of bricks at each end.

When a load is put on the central girder by a person sitting on it, the men’s arms and the anchorage ropes come into tension, and the men’s bodies from the shoulders downwards and the sticks come into compression.

The chairs are representative of the circular granite piers. Imagine the chairs one-third of a mile apart and the men’s heads as high as the cross of St. Paul’s, their arms represented by huge lattice steel girders and the sticks by tubes 12 feet in diameter at the base, and a very good notion of the structure is obtained”.

The contract for the bridge was awarded on 21 December 1882 and work started on the caissons to support the three cantilevers. By 1887, the year of Queen Victoria’s Golden Jubilee, the core of the cantilevers themselves had reached their full height and it remained to extend their arms towards each other and close the gap. In September 1889 a brigger clambered from the Queensferry to the central Inchgarvie cantilever across a ladder placed between crane jacks working on the cantilever arms some 200 feet above the water. On 15 October a more secure and formal crossing was made and by 6 November the central girder was ready to be connected. This was delayed for over a week until the temperature changed sufficiently to cause the necessary expansion to allow the key plates to be driven in and the girder fixed between its supporting cantilevers.

The bridge was formally opened by the Prince of Wales on 5 March 1890. It had taken 54,000 tons of steel, 194,000 cubic yards of granite, stone and con-crete, 21,000 tons of cement and almost 7 million rivets. It also cost 57 men their lives from a workforce of 4,600 at the height of construction.

Benjamin Baker was knighted in 1890. In addition to the Forth Bridge, he was also responsible for the development of the London “tube” system, the transport of “Cleopatra’s Needle” by sea from Egypt to Britain, and he acted as a consultant to the old Aswan Dam. He said of the Forth Bridge:

"If I were to pretend that the designing and building of the Forth Bridge was not a source of present and future anxiety to all concerned, no engineer of ex-perience would believe me. Where no precedent exists, the successful engineer is he who makes the fewest mistakes".

Text 6

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Read the text and say how tunneling methods have changed by now.

ANCIENT TUNNELS It is probable that the first tunneling was done by prehistoric people seeking

to enlarge their caves. All major ancient civilizations developed tunneling meth-ods. In Babylonia, tunnels were used extensively for irrigation; and a brick-lined pedestrian passage some 3,000 feet (900 metres) long was built about 2180 to 2160 BC under the Euphrates River to connect the royal palace with the temple. Construction was accomplished by diverting the river during the dry season. The Egyptians developed techniques for cutting soft rocks with copper saws and hol-low reed drills, both surrounded by an abrasive, a technique probably used first for quarrying stone blocks and later in excavating temple rooms inside rock cliffs. Abu Simbel Temple on the Nile, for instance, was built in sandstone about 1250 BC for Ramses II (in the 1960s it was cut apart and moved to higher ground for preservation before flooding from the Aswān High Dam). Even more elaborate temples were later excavated within solid rock in Ethiopia and India.

The Greeks and Romans both made extensive use of tunnels: to reclaim marshes by drainage and for water aqueducts, such as the 6th-century-BC Greek water tunnel on the isle of Samos driven some 3,400 feet through limestone with a cross section about 6 feet square. Perhaps the largest tunnel in ancient times was a 4,800-foot-long, 25-foot-wide, 30-foot-high road tunnel (the Pausilippo) between Naples and Pozzuoli, executed in 36 BC. By that time surveying meth-ods (commonly by string line and plumb bobs) had been introduced, and tunnels were advanced from a succession of closely spaced shafts to provide ventilation. To save the need for a lining, most ancient tunnels were located in reasonably strong rock, which was broken off (spalled) by so-called fire quenching, a method involving heating the rock with fire and suddenly cooling it by dousing with water. Ventilation methods were primitive, often limited to waving a can-vas at the mouth of the shaft, and most tunnels claimed the lives of hundreds or even thousands of the slaves used as workers. In AD 41 the Romans used some 30,000 men for 10 years to push a 6-kilometre tunnel to drain Lacus Fucinus. They worked from shafts 120 feet apart and up to 400 feet deep. Far more atten-tion was paid to ventilation and safety measures when workers were freemen, as shown by archaeological diggings at Hallstatt, Austria, where salt-mine tunnels have been worked since 2500 BC.

Text 7 You were told to write one page for the textbook on tunnel building. Use the following information. Do not forget to add pictures and charts.

FROM THE MIDDLE AGES TO THE PRESENT

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Because the limited tunneling in the Middle Ages was principally for mining and military engineering, the next major advance was to meet Europe’s growing transportation needs in the 17th century. The first of many major canal tunnels was the Canal du Midi (also known as Languedoc) tunnel in France, built in 1666 – 81 by Pierre Riquet as part of the first canal linking the Atlantic and the Mediterranean. With a length of 515 feet and a cross section of 22 by 27 feet, it involved what was probably the first major use of explosives in public-works tunneling, gunpowder placed in holes drilled by handheld iron drills. A notable canal tunnel in England was the Bridgewater Canal Tunnel, built in 1761 by James Brindley to carry coal to Manchester from the Worsley mine. Many more canal tunnels were dug in Europe and North America in the 18th and early 19th centuries. Though the canals fell into disuse with the introduction of railroads about 1830, the new form of transport produced a huge increase in tunneling, which continued for nearly 100 years as railroads expanded over the world. Much pioneer railroad tunneling developed in England. A 3.5-mile tunnel (the Woodhead) of the Manchester-Sheffield Railroad (1839–45) was driven from five shafts up to 600 feet deep. In the United States, the first railroad tunnel was a 701-foot construction on the Allegheny Portage Railroad. Built in 1831–33, it was a combination of canal and railroad systems, carrying canal barges over a summit. Though plans for a transport link from Boston to the Hudson River had first called for a canal tunnel to pass under the Berkshire Mountains, by 1855, when the Hoosac Tunnel was started, railroads had already established their worth, and the plans were changed to a double-track railroad bore 24 by 22 feet and 4.5 miles long. Initial estimates contemplated completion in 3 years; 21 were actually required, partly because the rock proved too hard for either hand-drilling or a primitive power saw. When the state of Massachusetts finally took over the project, it completed it in 1876 at five times the originally estimated cost. Despite frustrations, the Hoosac Tunnel contributed notable advances in tunneling, including one of the first uses of dynamite, the first use of electric fir-ing of explosives, and the introduction of power drills, initially steam and later air, from which there ultimately developed a compressed-air industry.

Simultaneously, more spectacular railroad tunnels were being started through the Alps. The first of these, the Mont Cenis Tunnel (also known as Fréjus), required 14 years (1857–71) to complete its 8.5-mile length. Its engi-neer, Germain Sommeiller, introduced many pioneering techniques, including rail-mounted drill carriages, hydraulic ram air compressors, and construction camps for workers complete with dormitories, family housing, schools, hospi-tals, a recreation building, and repair shops. Sommeiller also designed an air drill that eventually made it possible to move the tunnel ahead at the rate of 15 feet per day and was used in several later European tunnels until replaced by more durable drills developed in the United States by Simon Ingersoll and others on the Hoosac Tunnel. As this long tunnel was driven from two headings sepa-

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rated by 7.5 miles of mountainous terrain, surveying techniques had to be re-fined. Ventilation became a major problem, which was solved by the use of forced air from water-powered fans and a horizontal diaphragm at mid-height, forming an exhaust duct at top of the tunnel. Mont Cenis was soon followed by other notable Alpinerailroad tunnels: the 9-mile St. Gotthard (1872–82), which introduced compressed-air locomotives and suffered major problems with water inflow, weak rock, and bankrupt contractors; the 12-mile Simplon (1898–1906); and the 9-mile Lötschberg (1906–11), on a northern continuation of the Simplon railroad line.

Nearly 7,000 feet below the mountain crest, Simplon encountered major problems from highly stressed rock flying off the walls in rock bursts; high pres-sure in weak schists and gypsum, requiring 10-foot-thick masonry lining to re-sist swelling tendencies in local areas; and from high-temperature water (130° F [54° C]), which was partly treated by spraying from cold springs. Driving Sim-plon as two parallel tunnels with frequent crosscut connections considerably aided ventilation and drainage.

Lötschberg was the site of a major disaster in 1908. When one heading was passing under the Kander River valley, a sudden inflow of water, gravel, and broken rock filled the tunnel for a length of 4,300 feet, burying the entire crew of 25 men. Though a geologic panel had predicted that the tunnel here would be in solid bedrock far below the bottom of the valley fill, subsequent investigation showed that bedrock lay at a depth of 940 feet, so that at 590 feet the tunnel tapped the Kander River, allowing it and soil of the valley fill to pour into the tunnel, creating a huge depression, or sink, at the surface. After this lesson in the need for improved geologic investigation, the tunnel was rerouted about one mile (1.6 kilometres) upstream, where it successfully crossed the Kander Valley in sound rock.

Most long-distance rock tunnels have encountered problems with water in-flows. One of the most notorious was the first Japanese Tanna Tunnel, driven through the Takiji Peak in the 1920s. The engineers and crews had to cope with a long succession of extremely large inflows, the first of which killed 16 men and buried 17 others, who were rescued after seven days of tunneling through the debris. Three years later another major inflow drowned several workers. In the end, Japanese engineers hit on the expedient of digging a parallel drainage tunnel the entire length of the main tunnel. In addition, they resorted to com-pressed-air tunneling with shield and air lock, a technique almost unheard-of in mountain tunneling.

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PART II

Text 1

I. Listen and repeat: means cantilever trestle timber beam embed support suspension rope handrail drawbridge weight erect

[mi:nz] ['kxntIli:vq] ['tresl] ['tImbq] [bi:m] [Im'bed] [sq'pO:t] [sq'spenSn] [rqVp] ['hxndreIl] ['drO:brIG] [weIt] [I'rekt]

средство; способ консоль эстакада бревно, брус; строевой лес балка врезать, внедрять; закладывать опора подвешивание; подвес веревка; трос; канат перила; ограждение разводной мост вес сооружать; воздвигать; устанавливать

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Try to answer the questions, then read the text and check your ideas. 1. What does the word “bridge” mean? 2. What was the prototype of the first bridge? 3. What was the first bridge made of?

BRIDGES One of the outstanding statesmen once said in his speech “There can be little

doubt that in many ways the story of bridge building is the story of civilization. By it we can readily measure an important part of a people’s progress”. Great ri-vers are important means of communication for in many parts of the world they have been, and still are, the chief roads. But they are also barriers to communi-cation, and people have always been concerned with finding ways to cross them.

For hundreds of years men have built bridges over fast-flowing rivers or deep and rocky canyons. Early man probably got the idea of a bridge from a tree

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fallen across a stream. From this at a later stage, a bridge on a very simple bracket or cantilever principle was evolved. Timber beams were embedded into the banks on each side of the river with their ends extending over the water. These made simple supports for a central beam reaching across from one bracket to the other. Bridges of this type are still used in Japan and India. A simple bridge on the suspension principle was made by early man by means of ropes, and is still used in countries such as Tibet. Two parallel ropes suspended from rocks or trees on each bank of the river, with a platform of woven mats laid across them, made a secure crossing. Further ropes as handrails were added. When the Spaniards reached South America, they found that the Incas of Peru used suspension bridges made of six strong cables, four of which supported a platform and two served as rails.

All these bridges made possible crossings only over narrow rivers. The type of temporary floating bridge, the pontoon bridge, has been used for military pur-poses; military engineers can construct a temporary bridge on this principle, able to carry all the heavy equipment of a modern army, in an extremely short time.

The idea of driving wooden piles into the bed of the river in order to support a platform was put into practice 3,500 years ago. This is the basis of the “trestle” or pile bridge, which makes it possible to build a wider crossing easier for the transport of animals and goods.

With the coming of the railway in the 19th century there was a great demand for bridges, and the railways had capital for building them. The first railway bridges were built of stone or brick. In many places long lines of viaducts were built to carry railways; for instance, there are miles of brick viaducts supporting railways to London.

The next important development in bridge-building was the use of iron and, later, steel. The first iron bridge crossed the river Severn in Great Britain.

The idea of drawbridge, a bridge hinged so that it can be lifted by chains from inside to prevent passage, is an old one. Some Leningrad bridges were built on this principle. A modern bridge probably demands greater skill from a designer and builder than any other civil engineering project. Many things should be taken into consideration, and these may vary widely according to local conditions. In deciding what type of bridge is most suitable the designer has to allow for the type and weight of the traffic, and width and depth of the gap to be bridged, the nature of the foundations and the method of erecting the bridge. The designer has to calculate carefully how various loads would be distributed and to decide which building materials are more suitable for carrying these loads. IV. Give English equivalents to the following words and word combina-tions: поток, связь, консольный мост, канат, поручни, свая, понтонный мост,

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поддерживать, мостостроение, вбивать, с целью, посредством, разводной мост. V. Find 10 pairs of synonyms: VI. What notion is explained by the following definition? - a structure of wood, iron, concrete, etc, built to provide a way across a river, road, railway, etc. - a thing that bears the weight of something or prevents it from falling. - any of several boats or hollow metal structures joined together to support a temporary road over a river. - long ago, a structure over a moat of a castle that can be pulled up to stop people crossing. VII. Think of three words/word combinations from the text. Try to explain it using a pantomime and let the rest of the group guess it. VIII. Find the best continuation to the following ideas. The story of bridge-building is... . Early man got the idea of a bridge from... . The Incas of Peru used… . Suspension bridges are still used... . Floating bridges are able to carry... . A modern bridge demands… . Designing a modern bridge one should allow for… . IX. Answer the questions. 1. Why have people always been concerned with finding ways to cross rivers? 2. What did early man get the idea of a bridge from? 3. What types of bridges were evolved by early man? 4. Bridges of what type are used for military purposes? 5. When and why did the demand for bridges increase? 6. What are the functions of viaducts? 7. What was the important stage in bridge-building? 8. What things should be taken into consideration while designing modern bridges?

chief, fast, to evolve, secure, purpose, to construct, to put into practice, to hang, crossing, for example, to suspend, to build, for instance, to appear, to put into operation, safe, rapid, passage, main, aim

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Home Exercises I. Memorize the words from Ex. I page 12. II. Translate from English into Russian. Discuss the translation in your group. 1. The wine is roping. 2. While speaking she dropped a brick. 3. Slaveholders chain slaves. 4. Chains lift the bridge. 5. Farmers lift potatoes. 6. This family farmed two children. 7. This equipment is up to date. 8. He dates girls very often. III. Translate the sentences paying attention to the words: shall, should, will, would, to be, to have. 2. The load is distributed among all piles. 3. The builders are to erect the bridge in a year. 4. The chain was enough to reach the opposite bank. 5. You will have to take measures to prevent spring waters from penetrating the foundation. 6. I was told that a temporary bridge would be built across the river. 7. If the concrete were of a better quality, no cracks would appear. 8. Had the beams of that cross-section been used before, their defects could have been readily discovered. 9. You should increase the width of the bridge. 10. Our aim is to facilitate the work of the builders as much as possible. 11. Having widened and deepened the canal, they made it possible for use by ocean-going ships. 12. The road is being extended and widened, the surface layer – being replaced. IV. Describe the following types of bridges: a bracket bridge; a suspension bridge; a floating bridge; a drawbridge.

Text 2

I. Listen and repeat: expansion [Iks'pxnSn] растяжение

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overcome obstacle gorge artificial adverse calamity gallery revetment wall range ravine pedestrian

["qVvq'kAm] ['Obstqkl] [gO:G] ["Q:tI'fISl] ['xdvWs] [kq'lxmqtI] ['gxlqrI] [rI'vetmqnt wO:l] [reInG] [rq'vi:n] [pq'destrIqn]

преодолеть препятствие узкое ущелье искусственный неблагоприятный; вредный бедствие дренажная галерея; гидротехниче-ский тоннель подпорная стенка ряд; дальность; диапазон ущелье; овраг пешеход

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. First scan the text for about 10 minutes and answer the question: Is there any difference between “artificial structures” and “constructional works”?

CONSTRUCTIONAL WORKS ON RAILWAYS AND MOTORWAYS The history of civilization showed that roads were and still remain one of

the most important means for the development of the world economy. The re-mote areas make considerable demands on the expansion of road construction.

Arterial railways and motorways have to overcome different natural obsta-cles such as fast-flowing rivers, mountain ranges, deep and rocky gorges as well as urban structures. Men have built constructional works to provide a passage through these natural or artificial obstacles. The term «constructional works» denotes a collective totality of the structures used instead of the permanent way or subgrade at the intersection with different obstacles. Constructional works are aimed to protect the permanent way against the adverse environment effects or natural calamities and disasters strucks. The term incorporates the following structures: bridges, viaducts, aqueducts, overbridges, trestle bridges, culverts, tunnels, galleries, and revetment walls. The function of these structures is quite different from that of the civil engineering structures. That is why the term does not include buildings, wells, garages, etc., though they are also man-made struc-tures.

The word «artificial» cannot denote the constructional works, because this word is associated with the artificial building materials. But the term «construc-

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tional works» originated from the idea of the highest inventive, artistic skills, qualification and experience of the first railway engineers who were scientists, artists and builders simultaneously. They possessed profound knowledge in dif-ferent fields required for the erection of constructional works.

Constructional works are considered to be the most complicated ones and involve heavy outlays. Their share ranges from 15 to 50 per cent of the total capital investment for the road construction. But as a rule the total length of the constructional works does not exceed 5 or 6 per cent of the road length.

The obstacle determines the type and definition of the constructional works. At present there are more than twenty types of constructional works, which can be divided into two main groups: the bridgeworks and the tunnelworks.

A bridge is erected at the intersection of the road with a river or other water obstacle. But if a barrier is a narrow stream or a temporary channel it is much cheaper to construct a culvert. Such constructional works as viaducts, over-bridges and trestle works are often confused in an ordinary life. People have al-ways been concerned with finding ways to cross the gorges, canyons and ravines to speed the passage of traffic and pedestrians. They build viaducts to solve this problem and improve communication. A one-level traffic junction and a heavy traffic flow call for an overbridge providing traffic interchanges on more than one level.

A trestle bridge is built in cities when a traffic flow is affected by the houses, parks, and industrial areas. As a rule, a trestle bridge is rather long.

The tunnel types of constructional works are divided into tunnels driven through the mountain ranges and galleries located on the mountain slopes. They protect roads from stone downfalls, snow slips, avalanches, drifting and wet landslides. Retaining walls, revetment walls and balconies can provide a high degree of road protection from disasters. They are less complicated construction works. IV. Read the text word by word and complete the following words. G · · ge; artifi · · al; p · d · strian; aq · · duct; req · · re; galler · · s; leng · ·; impr · ve; str · · m. V. Make up word combinations as they are used in the text from the words given below.

water constructional stone retaining traffic road

protection wall junction bridge works obstacle

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trestle downfall VI. What do these attributes from the text refer to? Make up sentences of your own using word combinations with these words. Arterial, constructional, engineering, artificial. VII. Which of these words do you associate with constructional works?

obstacle easy aqueduct well complicated bridgeworks civil road building artificial shop protection invention demolishing

VIII. Complete the following sentences by writing no more than three words for each answer: 1. Some constructional works such as … have high architectural merits demon-strating a balance between art and science. 2. Constructional works are subdivided into ... . 3. … of the permanent constructional works is about 80 – 100 years and for temporary ones – about 10 – 15 years. 4. Tunnel operation requires the most considerable cost due to the problems of … . 5. Even the simplest constructional works call for great financial consideration during their designing, construction and… . IX. Answer the following questions: 1. What does the term «constructional works» mean? 2. What are the main possible obstacles, which railways and motorways have to overcome? 3. What groups can constructional works be divided into? 4. Why are viaducts, overbridges and trestle bridges often confused? 5. Is there any difference between retaining walls and galleries? Can they be confused? Give an example.

Home Exercises I. Memorize the words from Ex. I page 15. II. What is the English for: искусственные сооружения мостового типа; водопропускная труба; обли-цовочная стенка; горный хребет; путепровод; автодорога; снежные заносы; овраг; временный водоток; транспортные развязки; стихийные бедствия Make up a short story using these words in English (the more words the better).

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III. What verbal is used in the following sentences? What is its function in the sentence? Paraphrase the sentences using the Gerund instead of the In-finitive where it is possible. 1. Arterial railways and motorways have to overcome different natural obsta-cles. 2. Men have built constructional works to provide a passage through natural or artificial obstacles. 3. Constructional works are aimed to protect the permanent way against the ad-verse environment effects. 4. Constructional works are considered to be the most complicated ones. 5. If a barrier is a narrow stream or a temporary channel it is much cheaper to construct a culvert. 6. People build viaducts to improve communication. IV. Retell the text using the word combinations below. 1. The title of the story I want to tell you is… 2. First of all … 3. Second I would like to say that… 4. As far as I understand… 5. In fact… 6. As far as I remember… 7. In conclusion I’d like…

Text 3

I. Listen and repeat: superstructure pier abutment footing embankment flood control dam groynes river-bed floodplain bridge crossing bridge bearing underclearance estuary

['sHpqstrAkCq] [pIq] [q'bAtmqnt] ['fVtIN] [Im'bxNkmqnt] [flAd kqn'trqVl dxm] [grOInz] ['rIvqbed] ['flAdpleIn] ['brIG 'krOsIN] ['brIG 'beqrIN] ["Andq'k-lIqrqns] ['estjVqrI]

пролетное строение опора устой фундамент дамба, насыпь; набережная струенаправляющая дамба траверсы pycлo пойма мостовой переход опорная часть подмостовой габарит дельта; устье реки

II. Scan the following text for about 10 minutes and find the sentences with words from I (three words you will not find there).

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BRIDGE CROSSING AND ITS MEMBERS A bridge crossing is an engineering complex providing a safe and reliable

passing for traffic and water flow. It consists of a superstructure, supports or piers, abutments, footings, embankments, flood control dams, groynes.

Plain rivers have, as a rule, a clearly shaped low-water bed, i.e. the place where the river flows at the lowest water level. During the high-flood rivers overflow and cover the left and right floodplains. The floodplain areas are de-termined by the local relief and water level. Flood control dams and groynes regulate and direct the water flow during high-floods and protect embankments and pier footings from a scour.

The term «bridge» includes not only the superstructure but the substructure as well. The superstructure consists of spans directly resisting the load of the rolling stock. A span bridges the length between piers or supports. Substructure serves to support the superstructure of the bridge i.e. beams, girders, arches or trusses. It consists of abutments, piers and footings. Abutments and piers are supports resisting the vertical and horizontal forces from the spans, ice and wind. Vertical and slant legs transmit these loads to their footings. Footings re-ceive the loads from the supports and transmit them to the foundation bed.

Bridge bearings are located between the spans and supports to provide span deformation caused by the loads and seasonal changes as well as the temperature differences during the diurnal and night hours.

Bridge crossing must provide a free space between the supports and under the superstructure for navigation. It is called a clear span or a clearance. The dis-tance from high water to the lowest point of the superstructure depends on the river navigation class. All rivers are subdivided into seven classes. The largest and most important rivers call for the first class clearance in accordance with the navigation regulations. The required clearance in this case is 140 m wide and 16 m high.

The most important bridge characteristic is the span, i.e. the space between the bridge bearings of the neighboring piers. At present the bridge over the Hamber River in Great Britain built in 1981 is claimed as the world record for the span length of 1410 m.

Engineers and bridge builders have to pay due attention to the dead weight, the loads from the rolling stock and pedestrians as well as to the wind force and ice action, berthing impact, breaking force, temperature drops and seismic activ-ity (for the constructional works located in the earthquake-prone zones).

Bridge design must assure strength, rigidity and stability against the poten-tially destructive forces. Engineers take into consideration dead loads and live loads in design calculations of a bridge. III. Read the text carefully once again and make words from the letters (all the words are in the text).

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Sruptpo; Foigotn; cSuuprstutreer; ogrCsins; acneraCel; eraBgni; htWige; Snetghr; dPesentria. IV. Match the English and the Russian equivalents.

support bed dead weight rolling stock pedestrian design calculations berth

пешеход причал русло проектные расчеты опора подвижной состав собственный вес

V. Replace the words in bold with others from the list.

distance, demanded, pass, clear span, adjacent, classes 1. A span bridges the length between piers or supports. 2. Bridge crossing must provide a free space between the supports and under the superstructure for navigation. 3. All rivers are subdivided into seven groups. 4. The required clearance is 140 m wide and 16 m high. 5. Footings receive the loads from the supports and transmit them to the foun-dation bed. 6. The most important bridge characteristic is the space between the bridge bearings of the neighboring piers. VI. Read the text once again and say if these statements are true, false or not given. 1. Superstructure serves to support the substructure of the bridge. 2. All bridges are subdivided into several classes. 3. The loads from the supports are distributed on the spans. 4. The most important bridge characteristic is the span. 5. Engineers have to pay attention to the loads from the rolling stock and pedes-trians but not to the wind force and ice action, breaking force and temperature drops. 6. An engineer is a skilled person who designs, builds or maintains bridges, railways, etc. VII. Answer the questions without looking back at the text. 1. What does the substructure consist of? 2. What resists the vertical and horizontal forces from the spans? 3. What is a clearance? 4. What is the most important bridge characteristic? 5. What do engineers and bridge builders pay attention to?

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VIII. Complete the following sentences by writing no more than three words for each answer: 1. The loads developing reactions at the bridge may be subdivided into the dead load, … and the movable load from the rolling stock and pedestrians. 2. The most difficult problem for the calculation of the movable load is the ne-cessity of the … determination of the worst possible position of the rolling stock and pedestrians. 3. Ground washout can have disastrous … on bridges. 4. The span length … the clearance dimensions and financial considerations to minimize the cost of the bridge crossing. 5. During the Middle Ages the 72 m bridge span … the Add River held the re-cord for more than 400 years. 6. Overbridges, trestle bridges, viaducts have much in common during the de-sign and erection — the same dead, live and movable … . IX. Find one meaningless word and change it.

A bridge is a structure that waddies horizontally between supports, and its function is to carry vertical loads. The prototypical bridge is quite simple – two supports holding up a beam – yet the engineering problems that must be over-come even in this simple form are inherent in every bridge: the supports must be strong enough to hold the structure up, and the waddy between supports must be strong enough to carry the loads. Waddies are generally made as short as possi-ble; long waddies are justified where good foundations are limited – for exam-ple, over estuaries with deep water.

Home Exercises I. Memorize the words from Ex. I page 19. II. Change the Voice of the sentences where it is possible. 1. Substructure supports the superstructure of the bridge. 2. Vertical and slant legs transmit the vertical and horizontal forces to their footings. 3. Engineers and bridge builders pay attention to the dead weight. 4. Bridge design must assure strength, rigidity and stability against the poten-tially destructive forces. III. Make a plan of the text “Bridge Crossing and Its Members” using pic-tures instead of words or sentences. Render the text in Russian according to your plan.

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Text 4 I. Listen and repeat:

comprise [kqm'praIz] включать; содержать pipeline road-cum-rail bridge reinforced cable-stayed bridge beam bridge frame-type bridge beam-cantilever bridge combined half-through bridge through bridge through lattice truss bascule bridge

['paIplaIn] ["rqudkAm'reIl'brIG] ["ri:In'fO:st] ['keIbl'steId'brIG] ['bi:mbrIG] ['freImtaIp'brIG] ['bi:m'kxntIli:vq'brIG] [kqm'baInd'hQ:fTru: 'brIG] ['Tru: 'brIG] ['Tru: 'lxtIs'trAs] ['bxskjulbrIG]

трубопровод совмещенный мост (для автомобильного и ж/д транспорта) железобетонный вантовый мост балочный мост рамный мост балочно-консольный мост комбинированный мост с ездой посере-дине мост с ездой понизу сквозная ферма с ез-дой понизу разводной; подъем-ный мост

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Look through the text and say how bridges are classified in technical literature.

BRIDGES CLASSIFICATION

It has already been mentioned that bridges in a wide sense of this term mean constructional works comprising a superstructure and a substructure. In a narrow sense this term means a structure built to provide a crossing over a river.

In technical literature bridges are classified according to their indications as follows:

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Indication №1—by the main road function. 1.1. Railway bridges. 1.2. Motorway bridges. 1.3. Foot-bridges (Pedestrian bridges). 1.4. City bridges. 1.5. Pipe lines. 1.6. Metro-bridges. 1.7. Combined systems or road-cum-rail bridges (carrying various means of transport).

Indication №2—by the superstructure material. 2.1. Timber bridges (wooden bridges). 2.2. Stone bridges (masonry bridges). 2.3. Reinforced concrete bridges. 2.4. Metal bridges. 2.5. Steel reinforced concrete bridges (composite bridges). 2.6. Suspension bridges. 2.7. Cable-stayed bridges.

The suspension and cable-stayed bridges include the structures with the flexible stayed ropes as the main carrying element. Curvilinear ropes are used for suspension bridges and rectilinear ropes are used for cable-stayed structures. The ropes are made of metal wire strands and that is why suspension and cable-stayed structures can be regarded as variants of metal bridges.

Indication № 3 – by a structural model. 3.1. Beam bridges. (Spans of rectangular shape rest on supports). 3.2. Arch bridges. (A curvilinear structure produces a horizontal thrust through skewbacks to the supports). 3.3. Frame-type bridges. (Spans and supports are all indivisible rigid struc-ture). 3.4. Cantilever bridges. (These structures include cantilever arms, i.e. ele-ments built out of their supports). 3.5. Combined systems. (They consist of several simple structures – beam + arch).

Indication № 4 – by the position of the bridge floor. 4.1. Deck bridges. 4.2. Through bridges. 4.3. Half-through bridges.

Indication № 5 – by the overall bridge length. 5.1. Short bridges (up to 25 m long). 5.2. Medium bridges (from 25 to 100 m long). 5.3. Long bridges (more than 100 m long).

Indication № 6 – by the number of spans. 6.1. Single-span bridges.

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6.2. Double-span bridges. 6.3. Three-span bridges. 6.4. Multi-span bridges.

Indication № 7 – by the service life. 7.1. Permanent bridges. (Service life is 80-100 years.) 7.2. Temporary bridges. (Service life is about 10-15 years.) 7.3. Short-term bridges. (They are built for the period from two – three days to one year.)

In addition to the mentioned bridge types there are drawbridges (movable bridges), floating (raft) bridges and the ferrying. IV. Match the English and the Russian equivalents.

masonry bridge wire strand footbridge ferrying permanent bridge cantilever arm

пешеходный мост каменный мост консоль моста капитальный мост паромная переправа проволочная прядь

V. Use the words in the list to write the opposite of the phrases below. long, temporary, pedestrian, single-span, vertical, flexible

1 short bridge ≠ 2 multi-span bridge ≠ 3 permanent bridge ≠

4 motorway bridge ≠ 5 horizontal thrust ≠ 6 rigid structure ≠

What indication do the bridges from 1 – 4 refer to? VI. Complete the following sentences. Choose your answers from the box. There are more words than you will need. 1. City bridges comprise the structures built in a city which bear the loads from … and pedestrians. 2. The majority of railway bridges are … bridges because these structures are the safest under operation. 3. The bridge bearing of arch bridges transfer not only a vertical load to the supports but the horizontal … as well. 4. Frame-type bridges usually serve as overbridges or trestle bridges due to their small support … . 5. Combined systems are widely used in cities largely because of their … mer-its. 6. Temporary bridges and short-term bridges have as a rule … supports and steel spans. 7. Floating bridges are often used as … bridges.

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planes thrust length suspension architectural timber width short-term automobiles beam long-term

VII. Look at the following diagram. What is the base of this classification? Can you complete it? Draw a similar diagram in your notebook and let your partner complete it.

VIII. Complete the following sentences without looking back at the text. 1. The term «bridge» means … 2. According to their function bridges are classified into … 3. According to the superstructure material bridges are classified into … 4. A suspension bridge consists of … 5. Service life of temporary bridges is … 6. Combined systems consist of … 7. I know different types of bridges, for example … IX. Try to define types of the bridges in the pictures below.

Fig. 1

Railway

?

City

Pipe line ?

Road-cum-rail

?

Bridge

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Fig. 2

Fig. 3

Fig. 4

Home Exercises I. Memorize the words from Ex. I page 22. II. Describe different bridge structures using information in III and VI and your own ideas. Beam bridges, arch bridges, drawbridges, cable-stayed bridges, combined bridges, cantilever bridges, suspension bridges, permanent bridges.

Text 5

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I. Read the following text and say what information was new for you.

ON BRIDGE BUILDING Today bridge building is considered to be a science, but while it is of very

recent origin, it must not be thought that the previous centuries made no contri-bution to our knowledge of bridge construction. Everyone knows that there are in existence bridges that are believed to have been constructed over two thou-sand years ago. Even the idea of bridge has been given to man by nature. A tree accidentally fallen across a stream served to provide a safe crossing. To drop another tree at its side and to use strong creepers to bind them together must have been man’s first step in bridge building. Homer, who lived some time be-tween 800 and 1000 B.C. writes that bridges were common in his days and men-tions in particular pontoon bridges to be used for the passage of armies. Hero-dotes describes a bridge over the Euphrates, which must have been built at Babylon about 780 B.C. It was a short span structure thirty feet wide, made of timber beams resting on stone piers to carry its load. Another and later form of bridge and one requiring a higher degree of skill was the arch. The Romans are known to have brought this construction to its high degree of perfection. II. Give Russian equivalents to the following words and word combinations: of recent origin; to make contribution to; to be in existence; safe crossing; a pon-toon bridge; a span structure; timber beams; to rest; stone piers.

III. Complete the crossword puzzle.

Across:

1 – building 2 – a curved structure supporting the weight of something above it 3 – a structure, built to provide a way across the river, road, railway

1

1

2

2 4

3

5

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4 – a small narrow river 5 – a tall upright piece of stone, wood or metal used as a support for a bridge

Down:

1 – a thing made of several parts put together in a particular way 2 – anything that is being carried or waiting to be carried 3 – a long piece of wood, metal, concrete, usually supported at both ends, that bears the weight of part of a structure V. Answer the questions. 1. What is the origin of the first bridge? 2. What bridges were used for the passage of armies in Homer’s times? 3. Where was a short span structure built about 780 B.C.?

Home Exercises I. Use Passive constructions instead of Active ones. Model: The profession of an engineer is considered to be the most universal one. 1. We consider bridge building to be a science. 2. We believe many bridges to have been constructed 2000 years ago. 3. Nature has given to man the idea of bridge. 4. We know the Romans to have brought arch bridge construction to its high de-gree of perfection. II. Try to translate the text considering it to be: - a fairy-tail - a report - a terrifying story.

Text 6

I. Listen and repeat: cognitive solution variable perceive encompass appropriate valid

['kOgnqtIv] [sq'lu:Sn] ['veqrIqbl] [pq'si:v] [In'kAmpqs] [q'prqu-prIqt] ['vxlId]

познавательный решение переменная воспринимать; понимать; осознавать окружать; заключать (в себе) подходящий, соответствующий веский, обоснованный; юридически

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restriction weave verify simulate degraded comply reference overlook

[rI'strIkSn] [wi:v] ['verIfaI] ['sImjuleIt] [dI'greIdId] [kqm'plaI] ['refrqns] ["quvq'luk]

действительный ограничение плести; сплетать; соединять подтверждать; проверять; удостоверять моделировать; воспроизводить; имити-ровать находящийся в состоянии упадка; раз-мытый; понизившийся исполнять; подчиняться; соглашаться отношение; ссылка упускать из виду; не учитывать; про-глядеть

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Read the text and try to understand its main idea.

FORM AND STRUCTURE IN BRIDGE DESIGN The work of designing should be considered as a rational, cognitive process

in that it has to propose concrete solutions based on real needs. For a structure to be not only functional but also socially acceptable, there are a number of vari-ables involved, which can be divided into subjective and objective considera-tions. Subjective variables are qualitative in nature, having to do with aesthetics, with judgements of taste, which are not necessarily universal. The judging of a structure as handsome or ugly remains an individual opinion and thus highly problematic.

A proper method for the analysis of subjective variables, however, can lead to a choice of form, which is justifiable regardless of whether an individual per-ceives the work as handsome or ugly. This method should enable a project to be developed along lines that can command the validity of a logical process.

Statics define the structure, with direct consequences on the effects of light and colour, the way shadows fall, and the materials used. Statics, thus, define architecture. Following a design-method that considers the demands not only of statics, but of shape, context and the effects of light and colour will lead to a proposal which encompasses all relevant variables. These objective variables must be evaluated individually and as they relate to each other in order to iden-tify the most appropriate of the infinite number of possible design solutions for a given structure.

35

Considering statics in relation to shape, the basic conditions of the structure can essentially be reduced to the following three elements: the behaviour of the arch, which is chiefly subjected to axial load; the behaviour of the beam, which mainly undergoes bending moment; the combined behaviour of arch and beam, featuring a majority of axial load or bending moment, according to whether the arch or the beam component is prevalent.

Similar considerations hold true, for cable-stayed and suspended structures in which tensile stress prevails. In any event, various static schemes give rise to a project design, which can be formally valid, within its self-defined context.

Relationships between statics and shape are not restricted to the overall de-sign of the structure; but can also be used to define structural details. Thus, by “playing” with statics, various formal solutions can be reached, even for cable-stayed structures.

Statics is a science, which carried to a variety of equally valid formal solu-tions. But how to choose between them?

The structure, as a shape, may be said to produce an image of itself which is to be inserted in a spatial context. The term “context”, from the Latin cum + texqre, means to weave together and thus implies the combination of a number of variables. Every location has individual and unique features, stemming from the interplay of dimensional or distributional restrictions, and this is exactly where the difficulty lies in attributing a value, which may qualify a given con-text as “better” or “worse” than another.

The space itself is something, which already exists in nature. As soon as a man-made construction is placed within it, space is converted into place, and therefore becomes a context. The context produces a relationship between the structure and the effects of light upon it. The fundamental challenge is to avoid creating the wrong sense of scale.

Considering a structure from various observation points provides the means for verifying and simulating the impact of the structure on a given context while still in the design phase.

Geometrical aspects could also be taken into account, such as symmetry as a possible means for making the two banks on either side of the bridge alike, as opposed to asymmetry, which emphasises contrast. Perspective (from the Latin per-spicgre, to see through), or, better still, the optical science, which the ancient Greeks called optikhe, is the important theme for analysis by engineers.

If the area is degraded, it may be desirable to requalify it by proposing a de-sign which tends to emphasise the structure in relation to its context and thus to attract attention. On the other hand, in a project for an area of natural beauty, it would be more suitable to create a structure in harmony with its environment. It is worth remembering Menn’s words: “Engineering structures lean funda-mentally change urban and natural landscapes. The visual form of structures must therefore be selected with care. Bridges are among the most technically

36

challenging and culturally significant of engineering works [and] bridges can be regarded as a link between engineering and architecture…”

The statics and context of structures can be considered as follows: - statics is a science which proposes shapes which comply with its laws, but

a single static idea can yield a variety of shapes, all equally valid and acceptable; - context is a term of reference for choosing one of the various static shapes

by analyzing a whole range of other parameters. The choice between the various statically and contextually valid shapes is

made on the executive level. The final formal choice must comply in a general sense with the parameters of “construction theory” and, as specifically concerns the problems of the materials involved, but other variables, such as executive methods, costs, timing, inconvenience to users, must not be overlooked.

The choice of fabrication method may call for a construction yard on site, or for prefabricating elements elsewhere and then transporting them to the site. Pre-fabricated elements call for less equipment than traditional construction methods and thus take up less space in the area where the structure is to be built. On the other hand, a good road communications network is essential for the transport of particularly heavy and bulky elements, while a construction yard on site only re-quires a supply of concrete and reinforcement steel.

The use of prefabricated elements reduces construction time, thus reducing inconvenience to road users. Even the choice of one type of equipment as op-posed to another depends on evaluation of the problems specific to the area con-cerned, which may suggest the use of fixed scaffolding (e.g., provisional piers, usually made of metal) in some cases, or movable elements (e.g., a launching truck) in others. It is therefore the local conditions that dictate a certain type of solution!

So the focus shifts to the actual erection of the structure, meaning by this that the project cannot avoid taking into account the practical solutions involved.

IV. Match a verb from the left with a noun from the right. Make up your own sentences with the formed word combinations.

to insert to develop to identify to define to make to reduce to take

into account a project structural details in a spatial context a choice construction time the solution

V. Complete the definitions with the words in the box.

outline parts form circumstances

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Structure – a thing made of several … put together in a particular way. Context – … in which something happens or in which something is to be con-sidered. Design – a drawing or an … from which something may be made. Shape – the outer … or appearance of something. VI. Write positive or negative sentences using the text. 1. The work of designing / be considered / as a rational process. 2. The structure / define / statics. 3. Relationships between statics and shape / be restricted / to the overall design of the structure. 4. Geometrical aspects / can / be taken into account. 5. To create a structure in harmony with its environment / be important. 6. The project / can / avoid taking into account the practical solutions involved. VII. Read the text again and try to make a plan from the sentences below. Shape and context. Design as logical process. Justifiable forms. Statics and shape. VIII. What paragraph of the text can be described with the words? T.Y. Lin’s said: “The bridge as a structure must express the laws of nature, sim-ply and elegantly depicting the flow of force and the form of nature. There is in-herent beauty and economy in nature itself”. IX. Answer the questions. 1. Does the validity of the analytical method for determining structural shapes lie in its logical and rational parameters? 2. How can the aesthetic impact of civil engineering structures be reckoned, logically or according to an abstract philosophy? 3. Is a structure valid because it is aesthetically more or less attractive, or be-cause it is the outcome of a logical process, which can be quantified and veri-fied? X. Give an example of how local conditions can dictate a certain type of so-lution in erecting the structure.

Home Exercises

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I. Memorize the words from Ex. I page 29. II. Complete the word-building table.

Verb Noun form consider judge ………………….. direct ………………….. ………………….. reduce create

………………….. ………………….. ………………….. analysis ………………….. choice equipment ………………….. …………………..

III. Complete the sentences, use can + one of these verbs:

to use, to divide, to reduce, to lead, to avoid 1. There are a number of variables involved, which can … into subjective and objective considerations. 2. A proper method for the analysis of subjective variables can … to a choice of a justifiable form. 3. The basic conditions of the structure can … to three elements. 4. Relationships between statics and shape can … to define structural details. 5. The project cannot … taking into account the practical solutions involved. IV. Retell the text using the word combinations below. 1. The title of the story I want to tell you is… 2. First of all … 3. Second I would like to say that… 4. For your information… 5. As far as I understand… 6. In fact… 7. As far as I remember… 8. In conclusion I’d like…

Text 7

I. Listen and repeat: masonry thawing limestone adorn elimination density pile cribs

['meIsnrI] ['TO:IN] ['laImstqun] [q'dO:n] [I"lImI'neISn] ['densqtI] [paIl] [krIb] [paIn]

каменная кладка таяние; оттепель известняк украшать исключение плотность свая сруб; клеть; ряж

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pine larch arid cap dowel log square sawn timber plywood

[lQ:C] ['xrId] [kxp] ['dauql] [lOg] ["skweq'sO:n 'tImbq] ['plaIwud]

сосна лиственница высушенный насадка шпонка бревно брус клееная фанера

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. What building materials do you know? What advantages and disadvan-tages of different building materials can you find? Then scan the article and check your answer. IV. You are going to read a text about timber and masonry bridges. Five sentences have been removed from the text. Choose from the sentences A – E the one that fits each gap (1 – 5) to complete the text.

TIMBER AND MASONRY BRIDGES

The early bridges were made of stone and timber because these building ma-terials could be easily found everywhere. The earliest type of stone bridge is one that requires no designing. When large flat stones could be found it was a simple enough matter to build piers of square stones in the stream and lay the large flat slabs on the tops of the piers. Obviously, such a construction was very limited in application, for to find a flat stone large enough to span a reasonable distance was hard enough to start with, and when found would be difficult to handle with primitive tools owing to its weight. 1 The local name for these is clap-per bridges, and the Postbridge clapper bridge has three spans of 15 feet each. Such bridges are examples of beam or girder bridges in stone.

Stone used for bridge construction must be durable, weather proof and resis-tant to freezing and thawing. 2 Sometimes the builders use the arti-ficial stone i.e. concrete made of cement, crushed rock or pebbles, sand and wa-ter.

As the stones were “dressed”, that is cut, shaped and finished by stone ma-sons, buildings in dressed stone are called masonry. The greater the skill of the masons the longer does the building last, and this applies to bridges as well as houses and castles. Of course, wars and weather play their part too, but other

40

things being equal, a bridge built of carefully wrought masonry will last longer than one stuck together, as it were, with cement or mortar. The Romans knew this, although they were experts at making concrete. 3 But the Ro-mans frequently depended entirely on a good fit between the stones for many of their greatest works.

Today it would require quite careful design by engineers to construct a bridge by up-to-date methods, using modern materials. But the Romans had nothing to guide them but common sense and experience.

The masonry bridges offer the following advantages: 1. Long durability. Some Roman bridges survive to our days. The only reasons for their destruction are wars and disasters. 2. Aesthetic values of these bridges adorn many cities. 3. Greater rigidity under the extra heavy super load. 4. Considerable elimination of maintenance cost.

Possible disadvantages of masonry bridges are: 1. Greater dead weight as a stone density is between 2 and 2.7 t/m3 2. Only the arch structure may be used. It produces the horizontal force – the thrust, which requires powerful foundations and solid ground to rest on. 3. Masonry bridge construction is difficult to be mechanized. It requires much handwork. So it takes the builders much more time to erect a masonry bridge in comparison with other bridge types.

Timber bridges are used as temporary structures during 10 – 15 years. Piles and cribs made of wood are often applied as bridge foundations. 4 But metal spans save much time during bridge construction because they may be much longer than those made of wood.

The best timber for bridge building is pine, fur-tree and other soft wood as well as larch, arid cedar. 5 .

The expensive timber species such as oak, hornbeam, and beech are used only for the most important elements – the caps and dowels.

To increase its waterproof, timber is impregnated with antiseptics. It results in the service life prolongation up to 25 – 30 years. Plywood structures are widely used abroad and the spans made of this material are more durable, rigid and lighter than those made of logs and square sawn timber. A

Examples of bridges of this type are found in Cornwall and Devon, ow-ing to the prevalence of flat granite slabs on the moors, and a good ex-ample is still to be seen at Postbridge on Dartmoor.

B

Some of their bridge piers had, in fact, to be demolished by dynamite when the bed of the River Humber was deepened some 1500 years after their construction.

C

This sound wood is easily treated and does not decay.

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D

Most favorable rock for this purpose is granite, basalt, dolomite and widespread and rather cheap sandstone and limestone.

E

Wood is also used for bridge supports and spans.

V. Translate the following word combinations into English. деревянный мост, высокая прочность, высушенная древесина, временная конструкция, эксплуатационные расходы, твердый грунт, клееная фанер-ная конструкция VI. From the lists (1) and (2) write out the words with same meaning.

1) timber construct temporary eliminate adorn sound durable

2) solid momentary build wood strong cancel decorate

VII. Read the text again. Copy and complete the table.

Masonry bridge

Timber bridge

Building materials

Granite, ……………………

Pine, ……………………

Advantages

Long durability, ……………

Light, ……………………

Disadvantages

Difficult construction, ……

Decaying, ………………

VIII. Complete the following sentences by writing no more than three words for each answer: 1. Possible advantages of timber bridges are minimal construction cost, minimal weight of its elements for transportation and erection, ... , etc. 2. One of the disadvantages of timber bridges is … 3. The best timber species are … 4. Durability of a building depends on … 5. Most favorable rock for masonry bridges is … 6. While bridge building the Romans were good at …

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IX. Give answers to the following questions. 1. What were the earliest building materials for bridges? 2. What is the most durable material for bridge building? 3. What building materials are used for stone bridges? 4. Why were the bridges the Romans built very solid and durable? 5. What bridges are difficult to mechanize? 6. What material is used for timber bridge foundation? 7. How can the service life of stone and timber bridges be prolonged?

Home Exercises I. Memorize the words from Ex. I page 34. II. Translate the first sentence and complete the second one in each pair. Use the Past Participle. 1. In masonry bridges only the arch structure may be used. In timber bridges ___________ ___________. 2. Stone used for bridge construction must be durable. Concrete ____________ must be __________. 3. The timber such as pine, fur-tree, larch, arid cedar is easily treated. The timber species such as oak, hornbeam, and beech _________ _________. 4. Plywood structures are widely used abroad. Log structures ___________ ____________.

III. Describe the following structures. 1. Timber bridge foundations. 2. Timber bridge supports. 3. The basic types of timber bridge spans.

Text 8

I. Look at the following words for about 2 minutes and get ready to write them without looking back at the words. He who has no mistakes is the most attentive person in the group.

cantilever experience embankments neighbouring rectilinear curvilinear

rectangular indivisible length width II. Listen and repeat:

reinforced concrete bridge

["ri:InfO:st'kONkri:t 'brIG]

железобетонный мост

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substitute prestressed rein-forcement beforehand simple reinforce-ment slab superstructure ribbed span strut stiffening bottom chord web sleeper hole (aperture) curved jack wrought iron

['sAbstItju:t] ["pri: 'strest "ri:In'fO:smqnt] [bq'fO:hxnd] ['sImpl "ri:In'fO:smqnt] ["slxb 'su:pqstrAkCq] ["rIbd'spxn] [strAt] ['stIfnIN'bOtqm 'kO:d] [web] ['sli:pq] [hqul] ['xpqCq] ['kq:vd] [Gxk] ["rO:t'aIqn]

заменять, замещать преднапряженная ар-матура заранее обычная арматура плитное пролетное строение ребристое пролетное строение раскос жесткий нижний пояс балки стенка шпала отверстия отогнутый домкрат сварочная сталь

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. III. Scan the text for about 10 minutes. For questions 1 – 3, choose the an-swer (A, B, C, D) you think fits best according to the text. Then read the text again and check your answers. 1. Concrete has substituted natural stone in arch bridges because A it works well in tension. B it works well in bending. C it works well in compression. D it works well in torsion. 2. Prefabricated monolithic concrete is A usually called monolithic reinforced concrete. B the combination of monolithic reinforced concrete and prefabricated rein-forced concrete. C usually called prefabricated reinforced concrete. D the combination of monolithic reinforced concrete and prestressed concrete. 3. The disadvantages of the reinforced concrete bridges are

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A a substantial saving of steel; elimination of maintenance cost; greater rigidity. B the variety of structural forms; difficulties of concrete laying in winter; hidden bugholes. C hidden bugholes; a substantial saving of steel; elimination of maintenance cost. D great dead weight; difficulties of concrete laying in winter; hidden bugholes.

REINFORCED CONCRETE BRIDGES

Concrete being an artificial stone possesses the same good qualities as natu-ral stones. It works well in compression and bad in tension. That is why concrete has substituted natural stone in arch bridges because an arch works in compres-sion.

At the beginning of the 19-th century concrete was reinforced by metal bars. The idea was to transfer the tension stress from the concrete to the reinforce-ment. This resulted in a new building material, which is known as reinforced concrete.

At present reinforced concrete bridges are widely spread because this build-ing material is in line with short and medium spans (up to 40 – 60-m). It is also rather competitive with metal for long span structures.

The reinforced concrete spans are of a great variety because of their ability to work in compression and tension as well as flexure. It is used for producing simple beams, continuous beams, cantilever-beam systems, arches, frames and combined systems (arch + beam or arch + truss), etc.

The builders use monolithic reinforced concrete laid in situ, prefabricated reinforced concrete, which is made at the works beforehand and the bridge is as-sembled in-situ from the reinforced concrete segments. Prefabricated monolithic concrete is the combination of both mentioned types. To make the reinforced concrete highly strong and stiff it is prestressed by jacks and reinforcement of high strength wire.

Sometimes to reduce the structure weight they substitute the most usual coarse aggregate such as crushed rock, pebbles, and gravel by slag and bloating clay. This results in light concrete.

In comparison with other building materials the bridges made of reinforced concrete offer the following advantages: a substantial saving of steel, which is scarce to supply; elimination of maintenance cost as compared with metal bridges; greater rigidity as against metal bridges; long useful life (80 – 100 years); the variety of structural forms improving bridge appearance and architec-ture.

The disadvantages of the reinforced concrete bridges may be the following: great dead weight; great labor-consuming character of the bridge segments pro-ducing; hidden bugholes may cause dangerous complications and they are diffi-cult to be reconditioned; difficulties of concrete laying in winter.

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IV. Make up word combinations as they are used in the text from the words given below. Find and translate sentences with the completed phrases.

metal high-strength bug concrete structure prestressed

laying wire bar concrete holes weight

V. Fill in the correct words from the list. erected, reinforced, design, spans, longest, are

1. The longest spans among lattice trusses … 63m in Russia. 2. The first concrete arch bridge was … in France in 1875. 3. The first … concrete bridges were constructed in 1877. 4. The earliest Russian reinforced concrete beam bridge was built to professor Belelyubsky’s … in 1893. 5. The … spans among continuous beam systems are 105 m in Japan. 6. The longest … among arch bridges are 228 m in the Ukraine. VI. Read the text once again and make two columns of advantages and dis-advantages of reinforced concrete (do it in your notebook).

advantages disadvantages

VII. Cross out 3 words/word combinations, which cannot be used in de-scription of reinforced concrete. Prove your answer. Wide-spread, light, used for producing arches, rigid, durable, flexible, withstand great compression, relatively cheap, waterproof. VIII. Read the text and say if these statements are true, false or not given. 1. Concrete works well in flexure. 2. Reinforced concrete spans are the best for the lengths of 50 m. 3. Reinforced concrete is used for producing circular beams. 4. Light concrete can be made by substitution of slag and bloating clay for crushed rock, pebbles, and gravel. 5. Bugholes in reinforced concrete bridges always cause dangerous complica-tions. IX. Discuss in groups the following questions:

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1. Is there any difference between concrete and reinforce concrete? 2. What is the best length for the reinforced concrete spans and why? 3. What structural model is most preferable for the reinforced concrete bridges?

Home Exercises I. Memorize the words from Ex. I page 38. II. Open the brackets.

The first use of iron-reinforced concrete was by the French builder François Coignet in Paris in the 1850s. Coignet’s own all-concrete house in Paris, the roofs and floors (to reinforce) with small wrought iron I beams, still stands. But reinforced concrete development began with the French gardener Joseph Monier’s 1867 patent for large concrete flowerpots (to reinforce) with a cage of iron wires. The French builder François Hennebique applied Monier’s ideas to floors, (to use) iron rods to reinforce concrete beams and slabs; Hennebique was the first (to realize) that the rods had to be bent upward to take negative moment near supports. In 1892 he closed his construction business and became a consult-ing engineer, building many structures with concrete frames (to compose) of columns, beams, and slabs. In the United States Ernest Ransome paralleled Hennebique’s work, constructing factory buildings in concrete. High-rise struc-tures in concrete followed the paradigm of the steel frame. Examples include the 16-story Ingalls Building in Cincinnati, which was 54 metres tall, and the 11-story Royal Liver Building, built in Liverpool by Hennebique’s English repre-sentative, Louis Mouchel. The latter structure was Europe's first skyscraper, its clock tower reaching a height of 95 metres. Attainment of height in concrete buildings progressed slowly (to owe) to the much lower strength and stiffness of concrete as (to compare) with steel. III. Match the names of the people you have read about with their activities.

François Hennebique François Coignet Ernest Ransome Joseph Monier

- owned an all-concrete house. - patented large concrete flowerpots reinforced with a cage of iron wires. - used iron rods to reinforce concrete beams and slabs. - constructed factory buildings in concrete.

IV. You have built a reinforced concrete bridge. Why have you chosen this building material? Present your bridge.

Text 9

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I. Listen and repeat: deterioration deck alignment deficiency assimilate harsh warp surface scal-ing specimen spalling air entrain-ment

[dI"tIqrIq'reISn] [dek] [q'laInment] [dI'fISnsI] [q'sImqleIt] [hQ:S] [wO:p] ['sq:fIs'skeIlIN] ['spesqmIn] ['spO:lIN] ["eqrIn'tre-Inmqnt]

ухудшение; изнашивание, износ пролетное строение; настил выравнивание; выверка; горизон-тальная проекция недостаток; отсутствие поглощать; приспосабливать; сравнивать суровый; резкий деформироваться шелушение дорожного покрытия образец; экземпляр скол; откалывание; выкрашива-ние вовлечение воздуха (в бетонную смесь при приготовлении)

II. Look at the title of the text. What do you think it is about? Say words you expect to find in the text. III. Now read the text, check your guesses and say what the abbreviation NCHRP means, what it is famous for.

DETERIORATION OF CONCRETE BRIDGE DECKS

The US Interstate Highway System, with its strict alignment and grade re-quirements, has resulted in a need for vast numbers of bridges having reinforced concrete decks. Unfortunately, the rate of failure and deterioration of concrete bridge decks represents one of the major maintenance problems in the entire highway system. Because costs of correcting these deficiencies are usually far greater than the initial cost of the bridge deck, the potential value of a solution to bridge deck deterioration is immense.

In an effort to contribute to this solution, the National Co-operative High-way Research Program, which is administered by the Highway Research Board, entered into a contract with the University of Illinois to investigate the effects of stress on concrete durability.

The primary objective of the University of Illinois study was to determine if the durability of concrete bridge decks under assimilated harsh environmental conditions is significantly affected by stresses resulting from traffic, settlement, slab warping and volume changes in the concrete.

The experiments indicated that stress does play a slight part in freeze-thaw durability as regards surface scaling. Surfaces subjected to static tensile strength deteriorated at a slightly faster rate than did unstressed surfaces. On the other

48

hand, surfaces subjected to static compression or biaxial stress deteriorated at a slower rate. Slabs subjected to cyclic loading scaled faster than their unstressed companions; however, scaling was never observed to occur in a stressed spe-cimen without it also occurring in the unstressed companion.

The importance of obtaining adequate cover over reinforcing bars was also determined by the laboratory studies. The report spells out the various patterns of cracking experienced for different depths of concrete cover subjected to vari-ous loads simulating those assumed to result from corroded reinforcing steel. The University of Illinois research report does not conclusively solve the prob-lem of concrete bridge deck scaling and spalling. It does, however, shed light on the effects of stress in accelerating distress. It offers additional evidence con-cerning air entrainment, thermal characteristics, and the failure mode of cor-roded reinforcing steel, as well as suggestions for what might be tried in design and construction to produce more durable concrete bridge decks. IV. Give Russian equivalents to the following word combinations: reinforced concrete decks, the rate of failure and deterioration, concrete durabil-ity, freeze-thaw durability, volume changes, thermal characteristics, biaxial stress. V. Find 7 pairs of synonyms: VI. What is the English for the following word combinations? сделать вклад (в), подписать контракт, суровые условия окружающей сре-ды, предел прочности на разрыв, циклическая нагрузка, пролить свет (на), статическое сжатие

VII. Choose one of the words from the text and draw a picture about it. Show your picture to the group and let the group guess it. VIII. Find the best continuation to the following ideas. 1. The National Co-operative Highway Research Program entered into a con-tract with the University of Illinois to investigate the effects of stress on concrete durabillty because… 2. The primary objective of the University of Illinois study was… 3. Surfaces deteriorated at a faster rate while … and at a lower rate while …

major, spall, to study, to suggest, failure, speci-men, important, deficiency, pattern, significant, to offer, primary, crack, to investigate.

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IX. Work in pairs. Ask and answer the questions. 1. What represents one of the major maintenance problems? 2. For what purpose did NCHRP enter into a contract with the University of Il-linois? 3. What did the experiments indicate? 4. How did the slabs subjected to cyclic loading scale? 5. What else was determined by the laboratory studies? 6. What does the University of Illinois research report offer?

Home Exercises

I. Memorize the words from Ex. I page 42. II. Translate these word combinations paying attention to the Infinitive: the problem to be settled, to send the letter to inform them, the instrument to be used, to build the road to connect two towns, the story to listen to, the bridge to be constructed, the picture to speak of, the theory to be considered. III. Complete the sentences using the Infinitive. 1. He was happy… 2. Water is used… 3. This method was introduced in the factory… 4. In this area there are no bridges… 5. They took measures…

…to speak of. …to improve the work of the plant. …to have been working for many years with the famous scientist. …to make concrete out of ce-ment, sand and small stones. …to achieve better results.

Text 10 I. Listen and repeat:

alloyed steel rivet cast iron alloy recondition film girder

["xlOId'sti:l] ['rIvIt] ["kQ:st'aIqn] ['xlOI] ["ri:kqn'dISn] [fIlm] ['gq:dq] ['rIvItId

легированная сталь заклепка чугун сплав ремонтировать; переобору-довать пленка балка

50

riveted super-structure welded lattice truss connecting angles seam hanger traverse bracing crossbeam thrift high-strength bolt

'su:pqstrAkCq] ['weldId] ['lxtIs'trAs] [kq'nektIN'xNglz] [si:m] ['hxNq] ['trxvq:s 'breIsIN] ['krOsbi:m] ['TrIft] ["haI'streNT'bOlt]

клепаное пролетное строе-ние сварной сквозная ферма уголки шов подвеска поперечные связи поперечная балка экономность высокопрочный болт

II. Scan the text for about 10 minutes. For questions 1 – 3, choose the an-swer (A, B, C, D) you think fits best according to the text. 1. Metal bridges are made of A iron, steel, concrete. B oak, hornbeam, beech. C cast iron, timber, steel alluminium alloys. D cast iron, iron, steel alluminium alloys. 2. The low alloyed steel is A a strong hard metal made of iron and carbon. B a chemical element. C a strong hard metal made of iron and carbon with nickel, chromium, manga-nese, etc. D a hard type of iron made by casting it in a mould. 3. Metal bridges have certain advantages over other bridges such as A high material strength, durability, great possible span length. B commercially produced elements, great maintenance cost. C susceptibility to corrosion, high sensibility to the dynamic load. D durability, great maintenance cost. III. Now read the text carefully and check your answers.

METAL BRIDGES

Metal bridges may be constructed of cast iron, iron, steel alluminium alloys. The first cast iron bridge spanned the Severn in Great Britain in 1779. The length of the arched span was 32 meters.

In the 19-th century bridges were erected using wrought iron. At present metal bridges are built only of steel. That is why they can be called by another term – the steel bridges.

Steel is next to nothing as building material because of its rigidity and dura-

51

bility. Steel is easy to treat and recondition as compared to other building mate-rials. Low alloyed steel possesses the most perfect qualities because it contains rare elements – nickel, chromium, manganese, etc. The incorrodible steel brands are widely used at present. Recently these sorts of steel were only used in space industry. Such steel brands as «CorTen» in the USA and 10ХДDП in Russia form an oxide film on their surface making painting unnecessary.

Metal superstructures are the best for medium and long spans between 50 and 1500 meters. Metal structures are rather various including continuous and discontinuous beams, frames, arches, beam trusses, cantilever-beam structures, combined systems, etc. The length of these structures ranges within 150 m for discontinuous beams and within 500 m for cantilever-beam spans.

Frame spans have 100 m length limits. Beam trusses are used for the spans of 200 m long and arches are built for 300 m span length. Metal bridges can of-fer the following advantages: 1. High material strength. 2. Great possible span length. 3. Durability. 4. Commercially produced elements. 5. Convenient in erection, maintenance, overhaul and, reconstruction.

Due attention should be paid to the disadvantages of metal bridges: 1. Substantial consumption of hard-to-get steel. 2. Susceptibility to corrosion. (Metal bridges are lighter than those of any other material for a given task, but of course they have to be protected from corrosion and the weather, by painting or some other treatment. The painting problem can be quite substantial, as in the case of the Forth Bridge where, by the time the painters have reached the farther end it is time to start painting all over again!) 3. High sensibility to the dynamic load. 4. Great maintenance cost (painting).

Metal elements may be jointed by the following technique: a) welding; b) by rivets; c) by bolts.

Welding is the most thrifting method for saving materials but not so reliable as rivets and bolts. At present rivets are not widely used because their driving involves a very complicated technique. As for the high strength bolts, they are widely employed nowadays. IV. Match the English and the Russian equivalents.

алюминий низколегированная сталь ковкий чугун окислы металла чувствительность к динамической на-грузке

low alloyed steel alluminium wrought iron corrosion sensibility to the dynamic load

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металлические конструкции коррозия металла

metal oxide metal structure

V. Find 9 pairs of antonyms: VI. Fill in the adjectives from the text. Think of synonyms for each adjec-tive. Make up a short story using these synonyms. ... material ... maintenance cost ... qualities ... elements ... method ... technique VII. Fill in the correct word from the list below. What part of speech do they refer to?

fastening, heating, pressing, welding, according 1. A rivet is a metal pin or bolt for … two pieces of metal together, one end be-ing hammered or pressed flat to prevent slipping. 2. Rivet mounting is rather labor consuming and dangerous because it involves rivet … up to the red metal temperature. 3. To weld means to join pieces of metal together by hammering or … them when the metal is soften by heat. 4. Element welding of steel spans can be carried out at works by the special automatic … or in-situ by the manual welding. 5. Steel trusses built … to the standard design are widely used for spans from 33 to 132 m long. VIII. Find in the text the ideas to explain: - why metal bridges can be also called steel bridges. - why metal bridges are built only of steel although steel is next to nothing as building material. - why rivets are not widely used nowadays. IX. Answer the questions. 1. What is the best span length for metal bridges? 2. What are the advantages of metal spans? 3. What is the most reliable method for jointing the metal elements? 4. What is the length of trusses built according to the standard design? 5. What is oxide film is formed on?

rigid; erect; thrift; safe; demolish; soft; common; waste; reduce; plain; increase; dangerous; rare; perfect; weak; poor; strong; complicated

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X. Copy the table and complete it comparing timber, stone and metal bridges.

Timber bridge Stone bridge Metal bridge

Durability ─ + + High material strength Easy to mechanize Waterproof Convenient in reconstruction Welding is used Different shapes are possible

XI. You are given a task to design a bridge over the Irtysh River. What bridge it will be (timber, masonry or metal)? Explain your choice.

Home Exercises I. Memorize the words from Ex. I page 45. II. What is the Russian for: at present, is next to nothing, as compared to, such as, to pay due attention, as for Use these word combinations in the sentences of your own. III. Correct the statements. The first example is made for you. 1. The first cast iron bridge is being built now in Great Britain. – No, it is not. The first cast iron bridge was built in Great Britain in 1779. 2. In the 20-th century bridges were erected using wrought iron. – No, …………………………………………………………………………… 3. Steel is difficult to recondition as compared to other building materials. – No, …………………………………………………………………………… 4. Metal superstructures are the best for short and medium spans. – No, …………………………………………………………………………… 5. Metal bridges have more disadvantages than advantages. – No, …………………………………………………………………………… 6. Welding is the most reliable method as compared to rivets and bolts. – No, ……………………………………………………………………………

Text 11

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I. Listen and repeat: efficient argue retain high tensile weathering steel eliminate attempt

[I'fISnt] ['Q:gju:] [rI'teIn] ["haI'tensaIl 'weDqrIN 'sti:l] [I'lImIneIt] [q'tempt]

эффективный; продуктивный спорить; обсуждать поддерживать; сохранять атмосферостойкая сталь с высоким пределом текучести устранять; исключать попытка

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Look at the title of the article. What do you think it is about? Say words you expect to find in the text. IV. Read and check your guesses.

STEEL AND CONCRETE FOR HIGHWAY BRIDGES

The cost of bridges on motorways and other major roads can be cut signifi-cantly by a greater, and in some cases more efficient, use of steel instead of con-crete in bridge construction, according to a report published recently by the Highway Directorate of the Department of the Environment. The report argues that it is possible to save up to 30% of the cost of many bridge decks by using steel for the main members. The British Steel Corporation and the British Con-structional Steelwork Association were invited by the Ministry to participate in the study and retained an independent firm of consultants, C.J. Pell Prischmaun and partners, of 4 Manchester-Square, London W 1, to prepare new designs for bridges in consultation with Ministry. The study examined single and multi-span bridges, with spans ranging from 15 to 29 m, and the steel designs were based on the use of high tensile weathering steel (which does not require painting) to cut costs and eliminate maintenance. An alternative study was based on the use of nonweathering high tensile steel with a high-grade protection treatment sys-tem.

The Cement and Concrete Association has questioned the validity of the re-port and has said that the study attempts to draw comparisons between designs that are not comparable and that the steel designs prepared by the consultants do not comply with the Department’s own design criteria for bridges of this type. The Association also argues that the precast concrete beams examined in the study are less expensive than the compliers of the report assumed, whereas,

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since the time of the report, steel costs have risen some 10%. Another objection, says the Association, is that the steel designs are based on the use of weathering steel, which are not generally available. V. Give Russian equivalents to the following word combinations: independent firm of consultants, single and multi-span bridges, high-grade pro-tection treatment system, precast concrete beams. VI. Find the definition of the following prepositions. Use the prepositions in the sentences of your own. instead of according to of by since

- belonging to something; being part of something. - used for showing who or what does something. - from a specified time in the past until now. - as stated or reported by somebody or something. - as an alternative or replacement to somebody or something.

VII. Answer the questions to the text. 1. What is the way of cutting the cost of bridges on major roads? 2. What bridges were studied? 3. For what purpose was non-weathering high tensile steel with a high-grade protective treatment system used? 4. What has the Cement and Concrete Association questioned? 5. What are arguments of this Association? VIII. Fill in the gaps without looking back at the text. 1. It is possible to save ... of many bridge decks by using steel for the main members. 2. The British Steel Corporation and the British Constructional Steelwork Asso-ciation studied bridges with spans ranging.... 3. The Cement and Concrete Association reported that weathering steel is not... 4. C.J. Pell Prischmaun and partners is... IX. Give the summary of the text in 7 sentences.

Home Exercises I. Memorize the words from Ex. I page 49. II. Name the words, which these parts of speech were formed from: construction, significantly, recently, constructional, independent, consultation, treatment, comparison, comparable, precast, generally, available.

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III. Copy and complete the table. Find the sentences with these verbs in the text.

infinitive

past past participle

cut … … comply … …

drew … say … … … rose …

IV. Change passive constructions into active ones. Explain the use of the prepositions above in the following sentences. 1. The cost of bridges can be cut by a greater use of steel instead of concrete in bridge construction. 2. The British Steel Corporation and the British Constructional Steelwork As-sociation were invited by the Ministry to participate in the study. 3. The steel designs were based on the use of high tensile weathering steel. 4. An alternative study was based on the use of nonweathering high tensile steel.

Text 12

I. Listen and repeat: suspension bridge cable-stayed bridge stiffening girder anchor support flexible stayed cable curvilinear steel rope rectilinear cable stay tower merit slacking

[sq'spenSn'briG] ['keIbl-steId'briG] ['stIfnIN'gWdq] ['xNkq sq'pO:t] ['fleksqbl"steId'keIbl] ["kWvI'lInIq'sti:l 'rqup] ["rektI'lInIq] ['keIblsteI] ['tauq] ['merIt] ['slxkIN]

висячий мост вантовый мост балка жесткости анкерная опора гибкий кабель криволинейный стальной канат, трос прямолинейный ванта, канатная оттяжка пилон достоинство провес; ослабление

Find the words you have read in the text below and translate the word

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combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Do you know the difference between the suspension and cable-stayed structures? Read the text and find the answer to this question.

SUSPENSION AND CABLE-STAYED BRIDGES

Suspension and cable-stayed bridges are often confused. The matter is that they have very much in common: stiffening girders or trusses, anchor supports and hangers. And besides their main carrying element is a flexible stayed cable.

The difference between these two bridge types is determined by the two fol-lowing indications: 1. A suspension bridge has a curvilinear steel rope called a cable or a chain. 2. A cable-stayed bridge steel ropes are rectilinear. They are called cable stays.

The next indication is that suspension bridges usually have a continuous steel rope from the first tower top to the second one.

The Hamber Bridge in Great Britain is claimed as world record for a sus-pension structure because of its 1410 m span length. The cable-stayed bridge across the Freiser River in Canada has a 465 m span, which is the longest one for this sort of structures all over the world.

The basic advantages of the suspension and cable-stayed bridges are as fol-lows: 1. They provide the possibility to construct very long spans from 500 to 1500 meters. 2. High efficiency of these structures is due to the fact that the weight of one square meter of such spans is considerably less in comparison with other bridge systems. 3. Suspension and cable-stayed bridges offer more aesthetic merits. No doubt these structures are most attractive.

The disadvantages of the suspension and cable-stayed bridges are as fol-lows: 1. Low vertical stiffness, i.e. the structure greatly flexes under the live load. 2. Low horizontal stiffness, i.e. considerable shift due to the wind force in the horizontal plane. 3. High sensibility to the dynamic and aerodynamic loads.

High efficiency of the suspension and cable-stayed bridges is due to the fol-lowing factors: 1. The builders use the high strength wire with rated resistance 10000 MPa. 2. The chains and cable stays work only in tension, which is much easier than to

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work in compression. Working in compression the bridge elements may loose their stability. 3. There is no slacking in cables and cable stays, so the tension concentration is reduced to the minimum value. 4. Hangers and cable stays work as piers supporting a stiffening girder at many points. 5. The stiffening girder is free from working for its dead weight, which is transmitted, to the cable and the towers. This girder behavior becomes possible due to the special erection technique.

To make a stiffening girder lighter the designers employ the force regulation in cable stays. This results in most acceptable force distribution in bridge ele-ments beforehand.

IV. Guess the meaning of the words. A hanger, a steel rope, vertical stiffness, horizontal stiffness, high strength wire, a designer, a square meter, resistance. V. Complete the crossword.

Across: Down: 1 – висячий 1 – смещение 2 – пролетное строение 2 – опора 3 – жесткий 3 – эффективность 4 – цепь 4 – сплошной, непрерывный 5 – проволока 5 – растяжение 6 – нагрузка 6 – подвеска 7 – канат 7 – плоскость

1 3

4

3

6

7 5

4

7 2

5

6

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VI. Complete the following sentences by writing no more than three words for each answer: 1. The majority of cable-stayed bridges have a powerful stiffening girder made of … or reinforced concrete. 2. When suspension bridges are built without anchor supports the thrust is trans-ferred to the stiffening girder. In case the suspension bridge has the anchor sup-ports they transfer the thrust to the … . 3. One per meter run weight of a stiffening girder for suspension and cable-stayed bridges is considerably … in comparison with other bridge systems. 4. Erecting of towers is the most … working process for suspension and cable-stayed bridge construction. VII. Answer the following questions: 1. What are the basic advantages of suspension bridges? 2. What is the principle disadvantage of suspension and cable-stayed bridges? 3. What is the difference between cable-stayed and suspension bridges? 4. Does the stiffening girder work in tension? 5. Why is it necessary to apply force regulation for the cable-stayed bridges? 6. Why is a suspension span sensitive to the dynamic load? VIII. Read the following information and look at fig. 5, 6. Guess which story describes the construction of a suspension bridge and which story de-scribes the construction of a cable-stayed bridge. Match the stories with the pictures.

1. In the case of … bridges, foundations are made by sinking caissons into the riverbed and filling them with concrete. Towers are built atop the caissons. Next, the anchorages are built on both ends, usually of reinforced concrete with embedded steel eyebars to which the cables will be fastened. When the cables are complete, suspenders are hung, and finally the deck is erected – usually by floating deck sections out on ships, hoisting them with cranes, and securing them to the suspenders.

2. In the case of … bridges, foundations are made by sinking caissons into the riverbed and filling them with concrete. Then towers and anchorages are erected. After the tower is built, one cable and a section of the deck are con-structed in each direction. Each section of the deck is prestressed before continu-

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ing. The process is repeated until the deck sections meet in the middle, where they are connected. The ends are anchored at the abutments.

Fig. 5

Fig. 6

IX. Tell your group mates everything you know about suspension and ca-ble-stayed bridges.

Home Exercises I. Memorize the words from Ex. I page 52. II. Copy and complete the table.

Suspension bridge Cable-stayed bridge Differences

Advantages

Disadvantages

Text 13

I. Listen and repeat: footing trestle bridge precast support falsework

['futIN] ['tresl'brIG] ["pri: 'kQ:st sq'pO:t]

фундамент мост-эстакада сборная опора леса; подмости

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in situ precast with cast-in-place concrete sup-port dimension pit working sheet piling exhaust ram shrinkage grouting bed grout

['fO:lswWk] [in'sItju:] ["pri: 'kQ:st wID "kQ:stin'pleIs 'kONkri:t sq'pO:t] [daI'menSn] ['pIt"wO:kIN] ['Si:t"paIlIN] [Ig'zO:st] [rxm] ['SrINkIG] ["grautIN'bed] [graut]

на месте сборно-монолитная опора (линейный) размер обработка котлована шпунтовое ограждение вытяжка трамбовать; забивать усадка тампонажный слой бетона жидкий раствор; цемент-ный раствор; цементиро-вать

II. Scan the text for about 10 minutes. For questions 1 – 3, choose the an-swer (A, B, C, D) you think fits best according to the text. 1. The ordinary supports are made of A steel. B timber. C concrete. D limestone. 2. Footings are subdivided into A monolithic and precast footings. B large and small footings. C cable and hinged footings. D shallow and deep footings. 3. Builders make additional grouting bed A to strengthen the surrounding ground in the water. B to exhaust the water. C to place the falsework. D to avoid the shrinkage cracks. III. Now read the text carefully and check your answers.

SUPPORTS AND FOOTINGS CONSTRUCTION TECHNOLOGY In most cases bridge supports are made of concrete and reinforced concrete.

Steel supports are employed for over bridge and trestle bridges but not so fre-

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quently. The ordinary supports made of concrete may be subdivided into three

groups according to the construction technology: 1. Monolithic supports. The concrete is placed against the falsework in situ. The falsework determines the supports shape and dimensions. 2. Precast supports. The supports are mounted of the prefabricated concrete blocks. 3. Combined supports (precast with cast-in-place concrete supports). This sort of supports is practiced on a large scale and represents the structures assembled from the precast concrete blocks and monolithic concrete placed in situ.

Technological process of the support footing erection may be rather various and depends on a support structure. This process may be influenced by the geo-logical conditions, ground firmness, type and dimensions of the supports, loads from the spans and supports.

First, footings are subdivided into two large groups: shallow footings, deep footings.

Shallow footings are usually designed as monolithic ones on the natural bed. This is one of the simplest and rather cheap technologies but it can be employed only for firm grounds. The construction of such footing begins from the pit working. If a pit is excavated rather deep in a dry place for the abutments and over bridge supports as well as viaduct and trestle bridge supports, the builders employ a sheet piling. The same is done if a pit is excavated on a riverbed.

A sheet piling is made of metal bars driven to the calculated depth into the ground by a pile driver. Then several pumps exhaust the water from the sheet piling and after that the builders erect a falsework and install a reinforcement. Then they place concrete against the falsework and ram it in place. As a rule, the reinforcement does not work in tension but resists to the shrinkage cracks ap-pearing during concrete setting.

The most difficult work is to place the concrete for pier footings erected on the riverbed. The matter is that despite the pumps working some water enters the pit. That is why the builders make additional grouting bed to strengthen the sur-rounding ground in the water. And then they place the footing itself.

IV. Guess the noun which goes with the adjectives. Make up one sentence using all these 5 nouns. 1) timber, concrete, steel _ _ _ _ _ _ 2) monolithic, precast, combined _ _ _ _ _ _ _ _ 3) reinforced, prefabricated, precast _ _ _ _ _ _ _ _ 4) difficult, interesting, home _ _ _ _ 5) deep, coal, refuse _ _ _ V. What notions are described below? How are they reflected in the text?

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1) This term is a combination of the Greek “art, craft,” with “word, speech,” meant in Greece a discourse on the arts, both fine and applied. When it first ap-peared in English in the 17th century, it was used to mean a discussion of the applied arts only, and gradually these “arts” themselves came to be the object of the designation. By the early 20th century, the term embraced a growing range of means, processes, and ideas in addition to tools and machines. By mid-century, this notion was defined by such phrases as “the means or activity by which man seeks to change or manipulate his environment.” Today it is the de-velopment over time of systematic techniques for making and doing things.

2) These things are designed to convey the weight of a structure to the ground underneath and around it. They may be spread (made with wide bases placed directly beneath the load-bearing beams or walls), mat (consisting of slabs, usually of reinforced concrete, which underlie the entire area of a build-ing), or floating types.

3) It is a boxlike structure used in construction work underwater or as a foundation. It is usually rectangular or circular in plan and may be tens of metres in diameter. VI. Underline the correct word to complete each sentence.

A box caisson, open at the top/bottom and closed at the top/bottom, is usu-ally constructed on water/land, then launched, floated to position, and sunk onto a previously prepared foundation, leaving its upper edge under/above wa-ter level. It serves as a suitable shell for a pier, seawall, breakwater, jetty, or similar work, remaining permanently in place on the sea bottom.

An open caisson, closed/open at both the bottom and the top, is fitted with a cutting bottom edge, which facilitates sinking/floating up through soft material while excavation is carried out inside through a honeycomb of large pipes, or dredging wells. As excavating proceeds and the caisson sinks, additional sec-tions are added to the shaft above. This process is continued until the caisson has sunk to the required width/depth. A floor, usually of concrete, is laid to provide a bottom seal. The dredging wells can then be filled with concrete to complete the structure.

Pneumatic caissons are similar/different to open caissons except that they are provided with airtight bulkheads above the cutting edge. The space between the bulkhead and cutting edge, called the working chamber, is pressurized to the extent necessary to control the inflow of soil and water; thus the excavating can be performed by workmen operating in/out of the working chamber at the bot-tom of the caisson. VII. Match the verbs with the prepositions, which are used after them in the text. Choose 3 verbs and make up sentences with them.

to subdivide of

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to be made to depend to be influenced to resist

into by to on

VIII. Make up 7 special questions concerning the information about sup-ports and footings construction technology. Answer the questions of your partner.

Home Exercises I. Memorize the words from Ex. I page 56. II. Here are some adjectives from the text. Try to remember the nouns with which they are used. Form the comparative and superlative forms of the adjectives where it is possible. III. Render the following information in English. Use the words below. Earth foundation – фундамент на естественном основании; piled foundation – свайный фундамент; section – сечение; grillage – ростверк; hollow pile – свая-оболочка; drilled pile – буровая свая; coffer – опускной колодец; sinking – погружение.

В сложных геологических условиях, когда прочные грунты залегают на большой глубине, применяют фундаменты глубокого заложения. Данные фундаменты разделяются на несколько типов.

- Свайные фундаменты, состоящие из свай (т.е. железобетонных эле-ментов небольшого сечения и значительной длины) и ростверка – железо-бетонного элемента, объединяющего сваи.

- Фундаменты на сваях-оболочках. Их отличие от обычных свай в том, что сваи-оболочки представляют собой пустотелые цилиндры диаметром до 3,0 м и длиной до 30 м.

- Фундаменты на буровых сваях, которые отличаются от свай-оболочек только способом погружения свай.

- Опускные колодцы, представляющие собой железобетонную коробку, которая погружается до расчетной глубины.

- Кессонные фундаменты, которые отличаются от опускных колодцев тем, что работа в них ведется под давлением сжатого воздуха, чтобы от-теснить воду из кессона. Данный способ сооружения фундаментов очень

monolithic simple deep large cheap various dry metal difficult additional technological

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опасен для здоровья рабочих, подвергающихся перепаду давления воздуха в атмосфере и в кессоне.

В настоящее время не существует геологических и гидрологических условий, в которых нельзя было бы возвести фундамент глубокого зало-жения, являющийся более универсальным. Современные механизмы и технологии сооружения фундаментов и опор достигли высокого уровня. IV. You have heard that a construction company is going to build a bridge across the river you live by. Write a letter of complaint. Use the following expressions for your choice.

I am writing to complain about…; I am writing to express my strong dissat-isfaction with…; I was shocked by…; I insist that you…; I trust the matter will receive your immediate attention….; this is unacceptable…; I hope this matter will be resolved….

Text 14

I. Listen and repeat: hoist continuous beam incremental launching false nose bending moment overbridges built out concreting sliding formwork centering standard girder counterweight strap derrick-crane

['hOist] [kqn'tInju-qs'bi:m] ["InkrI'mentl 'lO:nCIN] ["fO:ls'nquz] ["bendIN'm-qumqnt] ['quvqbrIG] ["bIlt'aut kqn'kri:tIN] ["slaId-IN'fO:mwWk] ['senterIN] ["stxndqd 'gWdq] ['kauntqweIt] [strxp] ['derIk 'kreIn]

поднимать неразрезная балка продольная надвижка пролетного строения с применением конвейер-но-тыловой сборки аванбек изгибающий момент путепровод навесное бетонирование передвижная опалубка временные подмости (кружала) типовая балка противовес накладка мачтовый кран, деррик-кран

II. Read the text and pay attention to various techniques of superstructure

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erection (while reading you may make notes for better understanding).

BRIDGE SUPERSTRUCTURE ERECTION Erection technology depends on the span type, its dimension and material.

The simplest erection technique is applied for the standard beam spans. The standard reinforced concrete beams are produced at the precast works. The length of the spans for the motor way bridges ranges between 6 and 42 m. The railway bridge spans may be up to 34.2 m long.

The first method is described as following: the beams are transported by mo-torway or railway to the job site where one or two cranes hoist them to the de-signed position. When a bridge is designed as a continuous one the builders put the ordinary beams on two supports and join them into a continuous beam.

The next method of span erection is the following: reinforced concrete con-tinuous girders are cast on the bank and then the prefabricated segments are in-stalled by the incremental launching to the designed position. While being pushed the girder works as a cantilever resisting the dead weight. As reinforced concrete has a high density the builders use a false nose to reduce the bending moments in the girder. This method is used to construct very long span bridge. The technique has its disadvantages, which clearly limit its area of use: the con-crete has to be prestressed before and it needs time to reach certain age.

Two erection methods are used for framed suspended bridges, framed over-bridges and trestle bridges. The first one represents the built out concreting of a span in the sliding formwork. This structure is considered to be a monolithic one.

The next erection method represents the balanced cantilevering of framed structures from ready-made reinforced concrete segments produced at the pre-cast works. The segments are stuck together with epoxy resin or with cement. The reinforcement free length is welded. This method of construction leaves no possibility for later correction; the elements must be fixed exactly in the right position.

The most complicated erection technology is employed for arch bridges. The classical method demands temporary piers and centering to reproduce the shape of the arch superstructure to-be constructed. The precast reinforced con-crete blocks are placed on centering. The monolithic concrete arch is erected in the curvilinear formwork.

The erection of arches afloat is a much more advances technique. The arches and semi-arches are assembled on the bank and launched by the building ways to the barge, which carries these structures to the location. III. Replace the underlined words in each sentence with one word that has the same meaning. 1. Erection technology depends on the type of a distance between the supports.

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2. As reinforced concrete has a high relation of weight to volume the builders use a false nose to reduce the bending moments in the girder. 3. While constructing very long span bridge, the segments are stuck together with a grey powder, made by burning clay and lime that sets hard after mixing with water. 4. The erection of arches floating in water is a much more advances technique. IV. Match the similar words/word combinations:

1) erection 2) precast segments 3) moving of the assembled superstructure 4) structure for reducing the bending mo-ments under assembling 5) temporary structure for arch assembling 6) arch assembling with the aid of pontoons

a) assembling b) a false nose c) ready-made segments d) the erection of arches afloat e) centering f) incremental launching

V. What process from the given below is described? 1. Bridge construction 2. Erection of metal spans 3. Assembling of trusses

For this process standard girders or unified lattice trusses are used. The length of a standard girder is 55 m and of a unified lattice truss varies between 33 and 132 m. Metal beams are lighter than those made of reinforced concrete that is why they may be mounted by one or two cranes. When a girder is 55 m long it is cut into four blocks to facilitate its delivering to the site. A temporary pier is specially erected in the middle of the span. While erecting these blocks are placed by cranes on centering and supports. The blocks are joined by the high strength bolts. VI. Think of a span erection method, describe it to your partner using the text and let him guess. VII. Fill in the gaps with the words given below.

foundations; arch; support; falsework; superstructure; cables; cranes; self-supporting; welded; beam.

All bridges need to be secure at the _____ and abutments. In the case of a typical overpass _____ bridge with one support in the middle, construction be-gins with the casting of concrete footings for the pier and abutments. Where the soil is especially weak, wooden or steel piles are driven to _____ the footings. After the concrete piers and abutments have hardened sufficiently, the erection of a concrete or steel _____ begins. Steel beams are generally made in a factory,

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shipped to the site, and set in place by _____. For short spans, steel beams are usually formed as a single unit. At the site, they are placed parallel to each other, with temporary forms between them so that a concrete deck can be cast on top. The beams usually have metal pieces _____ on their top flanges, around which the concrete is poured. These pieces provide a connection between beam and slab, thus producing a composite structure.

Arches for _____ bridges are normally fabricated on-site. After the building of abutments (and piers, if the bridge is multiarch), a _____ is constructed. For a concrete arch, metal or wooden falsework and forms hold the cast concrete and are later removed. For steel arches, a cantilevering method is standard. Each side of an arch is built out toward the other, supported by temporary _____ above or by falsework below until the ends meet. At this point the arch becomes _____, and the cables or falsework are removed. VIII. What assembling methods are shown in the pictures below (fig. 7 – 9)? assembling of long arches assembling of aches on falsework assembling of discontinuous beams

Fig. 7 Fig. 8

Fig. ?

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Fig. 9 IX. Discuss the following questions: 1. How many erection methods are described in the text? 2. What common features do the methods of erection have for assembling steel girders and reinforced concrete beams? 3. What joint elements are used for the erection of framed bridges? 4. What types of spans are erected with the aid of jack-pushing the girders to-wards the designed position? 5. Describe the erection of arch bridges. 6. What is a temporary pier built for? 7. What is a false nose and why is it built up? 8. Why is a girder cut into blocks? 9. Why do the builders use centering for the arch assembling? 10. What is a formwork erected for?

Home Exercises I. Memorize the words from Ex. I page 61. II. Do the following puzzle and say the element of what bridge is described in it. A M E A B S I A D I SO T E B A C L T I N I E V ED E H W N E T I S C T J EP R O D R A W T O U , U S OE D T R P P T A E N OD N E . The construction of what bridge is similar to the construction of the bridge in the puzzle? Prove your answer. III. Tell your group mates what assembling methods you know. Describe them.

Text 15 I. Listen and repeat:

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fortress confluence moat conduit log launch alloy steel ensemble commemorate accommodate

['fO:trqs] ['kOnfluqns] [mqut] ['kOndjuIt] [lOg] [lO:nC] [q'lOI'sti:l] [On'sOmbl] [kq'memqreIt] [q'kOmqdeIt]

крепость слияние ров трубопровод; акведук бревно; полено запускать; начинать; пускать в ход легированная сталь ансамбль праздновать (годовщину); от-мечать снабжать; приспосабливать

II. You are going to read the text about Moscow bridges. What would you like to know about them? Write down at least five questions which you hope the text will answer. III. Now read the text.

MOSCOW BRIDGES

It was from the Kremlin, the first class fortress that Moscow originated. The Kremlin dates back to the 12-th century and was built upon the confluence of the Neglinnaya and the Moskva rivers, which protected the two fortress sides against enemy raids.

The Kremlin is a triangular shape in plan. So a wide and deep moat was ex-cavated for the fortress protection from the third approach to it. And the early Moscow bridges were built to span the moat. One of those bridges at Spassky tower was a timber bascule bridge. There was another bridge that spanned the Neglinnaya River at Troitsky tower. It was called the Troitsky Bridge. It has survived to our days though it is situated in a dry place now. We can see this bridge in the middle of Alexandrovsky Garden. The matter is that the Neglin-naya River was enclosed in conduits and driven underground.

Moscow was growing and in the 16-th century the idea of spanning the Moskva by the permanent bridge captured the minds. At those days the only crossing over the river from the Kremlin to Zamoskvorechye was made of tied logs. It was a floating bridge.

In 1643 Yan Cristler was invited to Moscow. He became the designer of the first arch bridge across the Moskva. It was the Big Stone Bridge (Bolshoy Kamenny Most) with seven spans resting on stone arches. Arch spans as de-scribed in historical records were 40 arshines or 28 m long. But if it had been so the total bridge length would have been 250 m long. It seems very doubtful be-cause the river width is considerably less. Evidently only one of the spans could

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be 28 m long and the rest of them were shorter. The old bridge was replaced in 1859. It was a three span cast iron bridge but the Moscovites were fond of its old name. Its main span was 63 m long and the length of the side spans was 36 m each. The roadway width was 16 m.

The modern Big Stone Bridge is not made of stone. It is a steel bridge with an attractive cast iron railing built in 1938 by engineer N. Kalmykov. It was erected under the Moscow Master Development Plan launched in 1932. The old bridges could not meet the requirements of the day and eleven bridges across the Moskva were built within an unprecedentedly short period. It took the builders only three years to erect them.

The modern Big Stone Bridge has three arch spans made of a highly reliable low alloy steel. The main span length is 105 m and its width is 40 m. The bridge can carry about 8 000 vehicles, 10 000 pedestrians and 120 trams per hour. A breathtaking view of the magnificent Kremlin ensemble situated on the slope of a gentle hill opens from the Big Stone Bridge spanning the Moskva River.

The Lefortovsky Bridge built in 1770 also belongs to the oldest bridge crossings across the Moskva River.

Altogehter, Moscow has about 200 bridges, most built since revolution. None of the 38 bridges across the Moskva River are alike. The Krymsky Bridge is the only suspension bridge across the Moskva River. Even though it is light and resembles openwork, it is six-lane structure. The bridge in Strogino is as-sembled of large ferroconcrete sections. The Moskvoretsky Bridge is a rather stark-looking bridge, whose monumental shape conforms well to the solid walls and towers of the Kremlin. It is the only bridge among the eleven bridges, which was erected of reinforced concrete and faced with pink granite. The bridge is supported by a gently sloping arch. Its main span is 95 m long. Built in 1936 – 1937 by engineer V. Kirilov to replace the old narrow bridge, it leads from Red Square to Zamoskvorechye, the district on the other bank of the Moskva. At pre-sent it is a foot-bridge as Red Square is not allowed for the city traffic.

The beautiful silvery Krymsky Bridge is the only suspension bridge across the Moskva supported by two steel chains flung across the tall pylons. Its main span is the longest over the Moskva. It is 168 m long. The wide road way ac-commodates six traffic lanes. The bridge was built in 1938 by engineer B. Kon-stantinov and architect V. Vlasov. Professor K. Yakobson who headed the «Bridges and Tunnels» department at the Novosibirsk Railway Engineering In-stitute during twenty-five years and was the dean of the «Bridges and Tunnels» Faculty took part in the design and construction of this bridge.

Many of Moscow bridges remember the glorious victories of Russian people and were even erected to commemorate those victories. The Borodinsky Bridge was constructed in 1912 to be a memorial of our victory over Napoleon’s troops. It is the only old bridge in Moscow preserving its original form. Have you found the answers?

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IV. Fill in the words from the list, then make sentences using the completed phrases. triangular, enemy, dry, river, iron, alloy, magnificent, short

… shape … raids … place … width

… railing … steel … building … period

V. Describe bridges from the left column using word combinations from the right column. Prove your answer by reading sentences from the text.

Bolshoy Kamenny Most Krymsky Bridge bridge at Spassky tower bridge from the Kremlin to Zamoskvorechye

arch bridge suspension bridge bascule bridge floating bridge

VI. Agree or disagree. Use the following expressions: That’s wrong, according to the text… That’s right, as far as I remember… You are quite right, as far as I know… If I am not mistaken… 1. Moscow has about 200 bridges built before the revolution. 2. The only suspension bridge across the Moskva River is three-lane structure. 3. The Moskvoretsky Bridge is erected of reinforced concrete and faced with red granite. 4. The smallest span of the Krymsky Bridge is 168 m long. VII. Put the sentences in the correct order according to the text. 1. In 1770 the Lefortovsky Bridge was built. 2. The Kremlin was built upon the confluence of the Neglinnaya and the Moskva rivers. 3. Yan Cristler became the designer of the first arch bridge across the Moskva. 4. The early Moscow bridges were built to span the moat. 5. Eleven bridges across the Moskva were built within three years. 6. In the 16-th century a floating bridge was built. 7. Many of Moscow bridges were even erected to commemorate the glorious victories of Russian people. 8. A three span cast iron bridge replaced the old Big Stone Bridge. 9. This bridge was erected of reinforced concrete and faced with pink granite. VIII. Copy and complete the table.

the modern Big the Moskvoretsky the Krymsky

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Stone Bridge Bridge Bridge engineer

date of construction

material

main span length

Home Exercises I. Memorize the words from Ex. I page 65. II. Change the following sentences, Active to Passive or Passive to Active. Make up your own sentences about Moscow bridges. Practice such models. 1. Motor traffic and pedestrians used the upper tier of the bridge across the Moskva in Luzhniki. 2. Pipe lines are built along the both Moskva banks. 3. All the joints have been firmly fastened together. 4. The bridge will be demolished next month. 5. The road of Krymsky Bridge accommodates six traffic lanes. III. Make up sentences from the following words. 1. The Krymsky Bridge / low alloy steel plates / a chain / hinges / is made of / has / jointed by / which. 2. Was / half-through bridge / in Luzhniki / in 1958 / a / combined / built. 3. What / the only / bridge / bridge / is / in Moscow / suspension? 4. The Moskvoretsky Bridge / used / why / as a / is / only / footbridge? 5. The first / over the Moskva / when / built / permanent bridge / was? 6. Many / how / have / spans / the early Big Stone Bridge / did? IV. Find additional information if you could not find the answers to your questions in the text. Speak about Moscow bridges.

Text 16 I. Listen and repeat:

prohibit islet tributary flourishing

[prqV'hIbIt] ['aIlqt] ['trIbjutqrI] ['flArISIN] ['mQ:stqpi:s]

запрещать; препятствовать островок приток; являющийся притоком процветающий; цветущий

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masterpiece admire coincide responce curb

[qd'maIq] ["kquIn'saId] [rI'spOns] [kq:b]

шедевр восхищаться; выражать восторг совпадать; соответствовать ответная реакция; срабатывание сдерживать; обуздывать

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Have you heard something about St. Petersburg bridges? Scan the text and write out the bridges of this city. IV. Now read the text and check all the bridges.

ST. PETERSBURG BRIDGES The early temporary St. Petersburg bridges were made by tying a row of

barges at anchor together. Some first bridges were timber or floating ones. Tsar Peter the Great prohibited bridge building in the young city in spite of the fact that it was situated on numerous islets of the Neva River Delta and its tributar-ies. Peter the First was eager to make the inhabitants employ vessels for crossing water obstacles. After his death in 1762 the Department for Bridges and Roads was established. That was the starting point for an intensive bridge erection to span numerous rivers, the Neva tributaries, canals, channels, etc.

Before 1834 sixty-five timber, twenty-six stone, ten floating and sixteen cast iron bridges were erected in St. Petersburg. It was a flourishing bridge age as the structures were of a high artistic value and had outstanding architectural merits. The Hermitage Bridge, the Winter Bridge, the Prachechny Bridge are among these masterpieces.

The most attractive bridges are in the parks of Tsarskoye Selo and a number of suspension bridges spanning the Fontanka River (fig. 10.1) and Griboedov canal. Seven suspension bridges were built in St. Petersburg between 1820 – 1840. Three of them survived to our days and we can admire the graceful Bank Bridge, the Lion Bridge and the Post Bridge.

The most famous among the destroyed bridges is the Egyptian Bridge (Yegipetsky Most). Four sphinxes decorate the bridge. It had 54 m span sup-ported by three heavy chains lying on towers. On the 20-th of January 1905 the bridge, which was 80 years old suddenly collapsed into the water bringing down everything and everybody that was on it.

The disaster was caused by a cavalry squadron crossing the bridge. The fre-quency of impact of the horses’ hooves coincided with the natural frequency of

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the bridge’s own vibrations resulting in a response powerful enough to bring the whole structure down.

In fact the real reason of the Egyptian Bridge collapse was the iron cold brit-tleness when metal looses its strength under frost.

The bridge was rebuilt 50 years later. No doubt you know the charming and elegant survived suspension footbridges with short spans and towers adorned with lions (the Lion Bridge) and gilt winged lion griffins (the Bank Bridge). Griffins were supposed to stand guard over gold as the bridge around 1800 led to the National Bank. The supporting chains come out of these animals’ jaws and make these bridges unique.

At the crossing of Nevsky Prospect (fig. 10. 2) and the Fontanka River you can see one of the world famous bridges. This is the Anichkov Bridge (fig. 10. 3). Following a decree of Peter the Great, a wooden bridge about 6 m wide was erected in 1715 by an Admiralty engineers battalion commanded by M. Anich-kov. It gave place to a stone structure with four towers on the comers in 1841. It has stood to this day and is as wide as Nevsky Prospect. Viewed from the water, the arch granite spans look graceful with its four sculptures of tamed horses by Peter Klodt. The series of sculptures represent a youth thrown to the ground, then rising to one knee and trying to tame the horse. The next episode shows the man on his feet but the horse is rearing. In the final scene the man’s will has won and the horse is finally broken. This is an allegory on the history of Peter the Great who managed to curb his enemies.

6

5

4

7 1 3

2

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Fig. 10

V. Fill in the correct word from the list below:

metal, cross, railings, permanent, longest, movable, foundation, long 1. Up to the middle of the 19-th century people could … the Neva (fig. 10. 4) only by the floating bridges. 2. The oldest … bridge, the Blagoveshchensky Most, was built in 1850. 3. Blagoveshchensky Most has seven spans, one of which is … to provide the ocean vessels of 50 – 60 m high traveling along the Neva. 4. The Liteiny Bridge (fig. 10. 5) is one of the few ones, which were not re-named; it is known for its wrought-iron … with Russian State Emblem. 5. Troitsky Most (fig. 10. 6) was built on the eve of the 200-th Anniversary of St. Petersburg … in 1903. 6. The Holy Trinity Bridge is a … arch bridge with one movable and four fixed spans. 7. The Palace Bridge (fig. 10. 7) which has five metal arch spans and a movable 57 m … span is strict and monumental. 8. The total length of the Alexander Nevsky Bridge, one of the two steel rein-forced concrete bridges, is 905 m. Its spans are the … among the Neva Bridges. VII. Look at the words in bold in the text above and try to explain them. VII. Match the phrases with their definitions. Find the given phrases in the text and then use them in the sentences of your own.

to be of a high value in spite of in fact no doubt to give place on the eve of

not being prevented from something to be replaced by something the quality of being useful or important on the day before the event very probably really

VIII. What words can you choose to describe St. Petersburg bridges? Name these bridges.

floating narrow high artistic value attractive timber suspension unique covered wooden graceful

cable-stayed movable monumental steel reinforced concrete IX. Answer the following questions using the text and exercise IV:

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1. Why were there only floating or timber bridges in St. Petersburg in the 18-th century? 2. What is the most famous among the suspension bridges? 3. When was the early bridge across the Neva built? 4. What bridge was never renamed? 5. What building material is the longest bridge across the Neva made of? X. Work in pairs. Act out similar dialogues using the prompts below. - What is the oldest bridge in St. Petersburg? - It’s the Blagoveshchensky Most. - Can you spell it, please? - B-L-A-G-O-V-E-S-H-C-H-E-N-S-K-Y. - Thank you. When was it built? - In 1850. - Sorry? - 1850. the Troitsky Most, 1903 the Yegipetsky Most, 80 the Anichkov Bridge, 1715 the Palace Bridge, 57 XI. Do you know another meaning of the word “bridge”? Read the dialogue and see if your idea is correct. - Well, Julian, what about a game? - Good idea, Sam. I’ll fetch the cards and you get the bridge table ready, will you? - Right you are. It’s over there by the fireplace, isn’t it? - Yes, it is. Oh, here’s Mike. Don’t bother; he’ll do it. - No bother at all. Does Mike play bridge? - No, he doesn’t. He prefers chess. - But we need two more players. What about Kate and Tom? - I think they are looking forward to play a game with such clever fellows. - Kate! Tom!… Complete the dialogue. Try to use the word “bridge” in its main meaning.

Home Exercises I. Memorize the words from Ex. I page 69. II. Translate the following sentences.

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1. Большинство мостов Санкт-Петербурга имеют арочные пролетные строения. 2. Характерной особенностью всех невских мостов является разводное пролетное строение. 3. Раскрывающиеся пролетные строения могут быть однокрылыми и дву-крылыми. Некоторые раскрывающиеся поворотные строения называют поворотными пролетами. Они горизонтально вращаются барабаном вра-щения. 4. После того как был построен мост Володарского, появилось много про-блем с его пролетным строением. Его пролетное строение состоит из ароч-ных ферм, так что это – мост с ездой по низу. Между арками и проезжей частью находятся тонкие подвески. Эти элементы сделаны из железобето-на, как и вся конструкция. В настоящее время бетон выщелачивается, что приводит к образованию трещин, а арматура страдает от коррозии. Вот по-чему мост Володарского реконструируется. III. What St. Petersburg bridge do you like? Make a report using some ad-ditional information.

Text 17

I. Listen and repeat: bearing elements joint vulnerable bearing capacity apron encase polygonal tracery spandrel composite super-structure

['beqrIN'elImqnts] ['GOInt] ['vAlnqrqbl] ['beqrIN kq'px-sqtI] ['eIprqn] [In'keIs] [pq'lIgqnl] ['treIsqrI 'spxndrql] ['kOmpqzIt 'su:pqstrAkCq]

опорные части соединение; стык уязвимый; ранимый несущая способность заслонка; козырек опалубить; вставлять; за-ключать многоугольный ажурная несущая стена сталежелезобетонное пролетное строение

II. Read the text and count Novosibirsk bridges.

NOVOSIBIRSK BRIDGES

At the end of the 19-th century the builders of the Transsiberian Railway had to bridge the mighty Siberian rivers. The overall length of this mainline

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from Moscow to Vladivostok is about 10 000 km. They erected unique magnifi-cent bridges at the intersection of waterways and the arterial railway.

The surveying group had chosen the site for a railway bridge across the Ob River and in 1893 the construction of the bridge crossing began at Krivoshchok-ovo village. A settlement that sprang up there during the years of construction developed into the largest city in Siberia.

Professor N. Belelyubsky greatly contributed to more than a hundred bridge projects. He designed the huge railway bridge across the Ob. This is a multi-span bridge which superstructure is a cantilever-beam metal truss. The under clearance is provided by 118 and 117 m shipping clearances. The main advan-tage of a cantilever-beam truss is that each support has one bearing part. This results in reducing of a support dimension at the bridge front. The suspended span is 87 m long and rests on the cantilevers of the adjacent trusses. No doubt the bearing joint of the suspended truss resting on a cantilever is the most vul-nerable bridge point. The reconstruction of this bridge began in 1981 as the bearing capacity of the bridge elements and the capacity of the riveted joints cannot resist a today’s current live load because of their previous service during 90 years. The ice aprons of the supports were encased in concrete. Then new metal trusses were put on this encasement. The old spans were redesigned and turned into welded trusses with triangular lattice, which are constructed to a standard design. Thus, the supports designed by N. Belelyubsky started their second century.

The next railway bridge across the Ob River was erected in 1935. It repre-sents a metal riveted truss with a top flange of polygonal shape. The bridge was constructed within a short period due to enthusiasm of young people. That is why it is called the Komsomolsky Bridge.

The communication between the Novosibirsk district situated on the right and left banks was provided by the floating bridge in summer and ice passage in winter till 1956. It retarded the city development. The Oktyabrsky Bridge was erected to solve the problem of communication and further industrial growth. * It was the first city bridge in Novosibirsk and proved to be one of the finest in our country. * The combined structure including a mighty metal girder and a flexible 126 m arch span adorns the magnificent city view. The tracery spandrel looks especially attractive. The bridge deck is made of reinforced concrete slab to make the carriageway covering much easier. * The bridge supports resisting the thrust from the arches might have looked rather ponderous but due to the nice granite encasement they decorate the bridge.

Not all the inhabitants of Novosibirsk know about the fourth bridge across the Ob River built in 1961. The matter is that this bridge crossing is situated along the Ob hydroelectric power station where the traffic speed is limited up to 5 – 10 kph.

The fifth bridge as well as the third one represents a city bridge. It was built

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in 1978 in the Dimitrov avenue alignment and bears the same name. The Dimi-trov Bridge is made of low-alloyed steel girder capable to work under the severe Siberian frost. The bridge represents a multispan continuous beam. The span length is 126 m. The most particular thing about this bridge is welding the metal on the job site. It was done for the first time in severe Siberian conditions. The welding technology was developed by the famous Paton Institute of Welding. The main trouble is caused by a welded seam. In terms of strength and durability the seam must be on a par with the base metal. The next peculiarity of the Dimi-trov Bridge is the joint effort of the metal girder and the reinforced concrete slab, which is placed on the girder’s top flange. Thus this superstructure is con-sidered to be a steel reinforced concrete or a composite one. * III. Find the equivalents to the following words. Make up your own sen-tences with these words and word combinations from I and III. возникать; опираться; переделывать; благодаря; исходя из; дело в том, что; подходящий для; вот почему IV. What does each of the following words from the text mean? mighty; intersection; suspended; enthusiasm; decorate

V. Read the information about Novosibirsk bridges once again and find the word that means the opposite of the word given.

ordinary _________________ to increase _________________ to end _________________ old _________________

long _________________ weak _________________ light _________________ difficult _________________

VI. Mark these sentences true, false or not given. 1. _______ The bearing capacity of the Dimitrov Bridge is kept at – 40, – 50 °C. 2. _______ The reconstruction of the earliest huge railway bridge across the Ob began because of impossibility to bear today’s loads. 3. _______ The railway bridge erected in 1935 is called the Oktyabrsky Bridge. 4. _______ Every citizen of Novosibirsk knows about the bridge situated along the Ob hydroelectric power station. 5. _______ The sixth bridge across the Ob is a Metro bridge put into operation at the end of 1985. 6. _______ The Oktyabrsky Bridge has a tracery spandrel. 7. _______ The Komsomolsky Bridge was constructed within a short period. 8. _______ The Dimitrov Bridge has a composite superstructure. VII. Answer the questions without looking back at the text.

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1. What Novosibirsk bridges do you know? 2. Who was the designer of many Novosibirsk bridges? 3. What was changed in the earliest railway bridge after reconstruction in 1981? 4. Why does the Oktyabrsky Bridge adorn the city? 5. What are the peculiarities of the Dimitrov Bridge?

Home Exercises I. Memorize the words from Ex. I page 74. II. Find the Infinitive in the sentences marked by (*) and define its function. III. Make a list of Novosibirsk bridges. Describe the structures of 4 bridges you like.

Text 18

I. How many Omsk bridges do you know? What are they? II. Scan the text for the information needed to fill in the blanks. 1. A bridge across the Irtysh will be built by ______________ and __________. 2. The bridge will be completed for __________ years. 3. According to the project this bridge will be a _______________ one. 4. Approach roads will connect the bridge to the ______________ at both banks of the river. 5. The bridge will have two _______________.

IRTYSH BRIDGE Irtysh River Bridge Construction Project, consisting of suspension bridge,

approach and access roads at both banks together with large and small structures in Semipalatinsk city is tendered by East Kazakhstan Oblast and Harima Heavy Industries Co., Ltd of Japan. According to the contract, which is dated 28th Janu-ary 1998 the Project will be completed within 42 months. The Project will be financed through a loan agreement entered in between the Republic of Kazakh-stan and OECF of Japanese Government.

The main structure of the Project is the Irtysh River Bridge, a suspension bridge with 750 m main span and 2 x 168 m approach viaducts. The bridge will carry 2 x 3 lane carriageway each lane being 3.75 m wide. This bridge is both economically feasible due to short construction period and gracious and full monumental, commemorating the independence of the Republic of Kazakhstan and representing the glorious future of the city of Semipalatinsk.

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On the left bank of the river approach road of 800 m length will connect the bridge to the left roundabout which will cross existing railway by two underpass bridges. Left approach road also contains a trumpet type interchange with an underpass bridge and toll plaza with operation and maintenance buildings. The road will extend from the roundabout to the junction of National Road in the di-rection of Almaty, inner city road the pontoon bridge and connection road to the Semipalatinsk Airport by 2060 m length access road. Furthermore about 440 m length of Airport connection road will be improved to cross-existing railway by underpass bridge.

On the right bank of the river 700 m length approach road which contains a trumpet type interchange with an underpass bridge will connect the bridge to the right roundabout. A 700 m length frontage road will connect Abai Street to ap-proach road by that interchange. The road will extend from roundabout to the junction of Omsk Road and Novosibirsk Road to the Siberian Region of Russia by 2390 m length access road.

The Project, when completed, will not serve only the urban traffic of Semi-palatinsk City but also to the transit domestic international traffics. III. Read the following characteristics and cross out those which do not suit the definition of the word. 1. Road: a way a) between places, b) long, c) with a prepared surface, d) for vehicles, e) with potholes. 2. Bridge: a structure a) made of wood, iron or concrete, b) heavy, c) difficult to build, d) across a river, road, railway. 3. Span: a distance a) loaded, b) between the supports, c) center. 4. Project: a piece of work a) organized carefully, b) drawn up by students, c) financed by the government, e) designed to achieve a plan. 5. Railway: a track a) long, b) from one city to another, c) with rails, d) on which trains run. IV. Read the text once again and give definitions of the following words, use them in the sentences of your own: roundabout, approach road, lane, toll, interchange, traffic. V. Find 8 pairs of antonyms:

complete, separate, begin, connect, damage, back, independent, subordinate, improve, rural, frontage, urban, extend, due to, shorten, because of

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VI. Correct the given sentences. Model: The Project has been completed for 42 months.

- Oh, no! The Project will be completed within 42 months! 1. The Project is being financed through a loan agreement. 2. The bridge

carries 2 x 3 lane carriageway. 3. This suspension bridge has 750 m main span and two approach viaducts. 4. On the left bank of the river approach road con-nects the bridge to the left roundabout. 5. The Project serves both the urban traf-fic of Semipalatinsk City and to the transit domestic international traffics. VII. Write an article describing the situation with the Irtysh River Bridge Construction Project.

Home Exercises I. Read the following article and render it in English.

Метромост через Иртыш – главная стройплощадка Омска в последние 5 лет. Как и во многих городах, находящихся по обеим сторонам крупных рек, в Омске проблема связи старой центральной части города и относи-тельно новой заречной стоит наиболее остро. Таким же типичным оказа-лось и решение этой проблемы: создание совмещенного авто- и метро- моста.

Строительство метромоста началось в декабре 2000 года. Новый мост соединил улицу Фрунзе с улицей Конева. Длина двухуровневого моста –650 метров. На его нижнем уровне расположен туннель метро, сверху про-ходит шестиполосная автомобильная магистраль с шириной проезжей час-ти 34 метра.

15 сентября 2005 г., в десять часов утра, начались первые испытания омского метромоста имени 60-летия Победы. Проверка была рассчитана на целый день, прочность сооружения испытывали 28 грузовиков.

Генеральная схема развития омского метро предусматривает строи-тельство трех линий метрополитена с пересадочным кольцом. Метромост позволит соединить центр Омска с левобережьем после ввода пускового участка первой линии метрополитена. По планам, это должно произойти в 2008 году. Четырем станциям первой линии омского метрополитена уже присвоены названия: "Библиотека им. А.С. Пушкина", "Кристалл", "Со-борная" и "Заречная".

Примечание. По расчетам областного правительства, объемы перево-зок первого пускового участка составят 190 тыс. человек в сутки, или 69 млн. человек в год. С вводом всей первой линии, включающей 11 станций, объемы пассажирских перевозок возрастут до 330 тыс. человек в сутки,

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или 140 млн. человек в год. На обслуживание пускового комплекса плани-руют задействовать 1200 человек.

Text 19

I. Listen and repeat: ferry continuous deck plate girder navigable cut groundwater table terrain silt prone loam tubular pile batter jib crane piling cap rig

['ferI] [kqn'tInjuqs 'dek 'pleIt 'gq:dq] ['nxvIgqbl] [kAt] ['graund"wO:tq 'teIbl] [tq'reIn] [sIlt] [prqun] [lqum] ['tju:bjulq 'paIl] ['bxtq] ['Gib 'kreIn] ['paIlIN 'kxp] [rIg]

паром неразрезная стальная со-ставная балка пролетного строения судоходный выемка, котлован уровень подземных вод местность, территория; площадка ил склонный суглинок трубчатая свая наклон стреловой кран свайная насадка установка; оборудование

II. Have you seen the Volga River and its bridges? What are they? Read the following text and find the answers to the following questions: 1. How many levels is the new bridge intended to carry traffic on? 2. What is the length of the designed bridge? 3. Why is a clear height of the bridge not less than 16 m? 4. What does the riverbed consist of? 5. How many piles are there under each pier? 6. How were the construction works on the river piers performed?

NEW BRIDGE ACROSS THE VOLGA RIVER, RUSSIA

Kineshma and Zavolzhsk, two industrial cities in the Ivanovo region facing each other across the banks of the Volga River, have had no direct transportation connection. The existing ferry crossing could not accommodate the growing road traffic, whereas railway transit between the two cities is inefficient because

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of considerable detour lengths. The bridge project over the Volga presently under construction will provide

a link for the railway lines and highways between the two cities, as well as for the neighbouring Central European territories of Russia to the northeast. The crossing route was planned away from Kineshma’s and Zavolzhsk’s centres, bearing in mind their future development and the requirements of the combined transport use (i.e., water, railway and road) on a regional scale. The new bridge is intended to carry traffic on two levels, the railway on the lower level and the highway on the upper. The superstructure is designed as a continuous steel lat-tice girder with two traffic levels. The railway superstructures on the left bank are single-span steel deck trusses; the highway superstructures on both banks are composite continuous deck plate girders. The dual carriageway is 9.5 m wide, with two 1.5 m wide sidewalks.

The crossing includes the main bridge across the Volga and five viaducts, (of which one is to carry a railway, the other four accommodating highway traf-fic). A new railway line will pass under the viaducts.

The entire length of the crossing is 15.9 km, the bridge over the Volga being about 1900 m long. The civil works are to be carried out in two stages. First, railway traffic will open and during the second stage the construction will be completed for road traffic.

The height of the bridge and the length of the spans in the riverbed part were chosen based on the dimensions and the structure of the deck and to comply with the current regulations on bridge clearances. These regulations call for a clear height of not less than 16 m, and a navigable span length in the clear pas-sage of not less than 140 m. The elevation of both rail and road levels has been adjusted accounting for the depth of the approach cuts, bearing in mind the pro-vision that their lower edges must remain above groundwater table. The differ-ence between the road and rail levels is 17.05 m.

The terrain of the crossing is of complex geology. The riverbed consists of silts and sands with varying grain size, prone to flood erosion. Further down, there are gravel layers containing sand, then loams and sands, with hard clays underlying all. The foundations of the bridge piers in the 1100 m wide riverbed zone bear upon vertically driven cast-in-place piles, 1.5 m in diameter; the land piers are mainly supported by driven precast concrete piles of 0.6 m diameter. The piers were designed to withstand the ice loads of blocks up to 0.9 m thick and up to 300 x 400 m in size.

The abutments of the bridge are of cast-in-place concrete bearing on 0.6 m diameter tubular piles driven to a depth of up to 18 m below the river bottom. The number of piles under each pier is from 48 to 56. Some of the piles are driven vertically; others are driven in a batter of 4:1 to 10:1. Some of the pier foundations include prism-shaped concrete piles!

All the construction works on the river piers were performed afloat using

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floating jib cranes and scows to transport structural elements and materials. Dur-ing the winter, the ice cover was broken in order to ensure navigation for these vessels. Prior to piling works, steel casings were sunk to the required depth. Then, bore holes were drilled inside the casings reaching 29-32 m deep from the bottom level of the piling cap, reinforcement cages lowered and concrete mix poured.

The stability of the superstructure in erection was ensured by securing it to the protruding longitudinal girders of the spans already erected, application of temporary connector devices in truss chords and by other means in accordance with the erection procedure charts. The members to be erected were supplied via a temporary rail track laid on the railway deck. To lay the concrete decking slabs, special erection rigs were used. III. From the words below make up word combinations as they were used in the text. Ferry, railway, lines, crossing, tubular, table, erection, rigs, piles, structural, clear, passage, elements, groundwater. IV. Match the given words with their common and special meaning (consult the dictionary). In what meaning are these words used in the text? Common meaning Special meaning cut clearance batter support link cap chord concrete size

1) поддержка 2) связь 3) кепка 4) устранение препятствий 5) струна 6) разрез 7) конкретный 8) размер 9) кляр, жидкое тесто

a) опорная стойка b) наклон c) шарнир d) отверстие (моста) e) насадка f) пояс (фермы) g) бетонный h) клей i) выемка

V. Are these statements true or false? 1. The bridge over the Volga will provide a link for the highways and railway lines. 2. The new bridge is intended to carry traffic on four levels. 3. The highway is designed to be on the lower level and the railway on the up-per. 4. The dual carriageway is 9.5 m wide, with a 1.5 m wide sidewalk. 5. The entire length of the bridge over the Volga is 15.9 km. 6. A clear height of the bridge is not over than 16 m. 7. The riverbed consists of loams, sands and hard clays. 8. Some of the piles are driven horizontally.

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9. The protruding longitudinal girders of the spans, temporary connector de-vices in truss chords ensure the stability of the superstructure. VI. Copy and complete the table.

bridge across the Volga River region Ivanovo levels 2 width of a carriageway length of the bridge construction stages clear height ground pile diameter a number of piles

Home Exercises I. Memorize the words from Ex. I page 79. II. Make a drawing of the bridge in question, put dimensions and describe the bridge.

Text 20

I. Listen and repeat: launching lateral duct prestressing plane splice pylon flange

['lO:nCIN] ['lxtrql] [dAkt] ["pri:'stresIN] [pleIn] [splaIs] ['paIlqn] [flxnG]

надвижка боковой; вторичный; ответвление; отвод воздуховод предварительное напряжение плоскость соединение, стык; сращивание пилон; опорная стойка полка, пояс (балки)

II. Read the following text and write out the key words.

SOUTH BRIDGE OVER THE DNEPR RIVER IN KIEV

The new South Bridge over the Dnepr River in Kiev, Ukraine, consists of a 564.5 m long cable-stayed portion with a main span of 271 m, and a concrete approach viaduct with a total length of 662 m. The bridge carries a six-lane roadway, two rail tracks and four large-diameter water pipes.

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Stiffening girders on the main span side of the pylon are continuous three-span steel box girders, while on the opposite side the girders are segmental prestressed concrete box sections. The three-span continuous box girders are made of low-alloy steel with a minimum yield strength of 390 MPa. The shop-fabricated components were welded. Field splices were either welded or joined by high-strength bolts. Bolting was used where automatic welding was impracti-cal because of the short length of the weld or because of difficult access.

The steel girders were preassembled on the shore and erected by launching. The girders were equipped with a launching nose and stiffened with a temporary strut system.

Because of the considerable width of the bridge, 42 m, the bearings at the piers permit lateral displacement of the superstructure. At the pylon, hinged conditions are provided by supports with limited rotational capability in the ver-tical and the horizontal planes.

In order to provide the necessary counterweight mass, concrete rather than steel was needed for the two-span anchorage girder. The anchor spans consist of modified K-type concrete box segments used in the approach spans. Exterior cross section dimensions were retained; but thicknesses were increased and new duct openings for the lateral and vertical prestressing were provided, as were ledges for anchorage of added prestressing strands.

The stay cables are anchored in the cast-in-place concrete of the longitudinal splices between precast box sections. Anchorage concrete is pre-stressed trans-versely by strands joining the walls of adjacent precast sections and longitudi-nally by 36 cables, each with a prestressing force of 2950 kN. The vertical and the transverse tensioning cables through the anchorage zones effectively join the precast and the cast-in-place portions of the cross section into a monolithic structural entity. At the end support of the anchor spans, tie down to the pier is accomplished by means of 16 vertical anchor cables of the same size as the ca-ble stays.

The pylon is a two-legged cast-in-place concrete frame with two precast concrete cross struts. Its legs are located in the space between the roadway and the rail tracks. Cost comparison between steel and concrete pylons showed that the former would be about four times more expensive. Aside from reasons of economy, concrete was judged to lend itself better to architectural treatment.

Several solutions for the pylon-girder junction were studied. Eccentric hinged connections between the bottom flanges of the stiffening girders and the pylon were chosen. This scheme best solves the problem of joining the steel and the concrete superstructures, and considerably reduces the bending moments in the girders.

The aerodynamic stability of the bridge and its principal elements was in-vestigated by calculations and wind tunnel testing. Stress distribution in connec-tions was verified on models.

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III. Find 7 pairs of synonyms: IV. Fill in the most suitable word. 1. The bridge over the Dnepr River carries a six-… roadway. a) linen b) line c) lane 2. The girders are made of low-alloy… . a) stool b) steel c) still 3. Bolting was used where automatic welding was… . a) imperfect b) impractical c) impressible 4. The girders were stiffened with a temporary … system. a) stub b) street c) strut 5. The stay cables are … in the cast-in-place concrete. a) anchored b) angered c) annoyed 6. Concrete lends itself better to architectural … than steel. a) transshipment b) trimmer c) treatment V. Match the beginnings with the endings.

1. The bridge carries… 2. The box girders are erected … 3. The steel girders were… 4. The anchor spans consist… 5. The aerodynamic stability of the bridge was investigated…

a) … by launching. b) … a roadway, two rail tracks and four water pipes. c) …of concrete box segments. d) … by calculations. e) … made of low-alloy steel.

VI. Make up questions from the words and answer them. 1. What / over / the new / the Dnepr / South Bridge / does / of / consist? 2. Stiffening / what / the / made / are / girders / of? 3. How / assembled / the / were / girders / steel? 4. What / to provide / mass / made / the necessary / was / counterweight? 5. What / the / look / does / pylon / like? 6. What / the pylon-girder / you / junction / say / can /about? 7. Was / distribution / connections / stress / verified / in?

Home Exercises

previous, continuous, extra, uninterrupted, main, equal, temporary, short-term, costly, added, the same, former, expensive, principal

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I. Memorize the words from Ex. I page 83. II. Paraphrase the sentences using the Passive Voice. 1. High-strength bolts fixed field splices. 2. They preassembled the steel girders on the shore. 3. A temporary strut system stiffened the girders. 4. They used modified K-type concrete box segments in the approach spans. 5. The location of pylon legs is between the roadway and the rail tracks. III. Tell everything you know about the new South Bridge over the Dnepr River in Kiev using your key words.

Text 21

I. Listen and repeat: comprise dead weight shear connector groove hollow

[kqm'praIz] ["ded 'weIt] ['SIq kq'nektq] [gru:v] ['hOlqu]

включать; содержать собственный вес шпонка; анкер; жесткий упор паз, канавка полость, углубление; выемка; полый

II. Why is it necessary to strengthen bridges? Is it done often or seldom? Why? Read the text and say why the road bridge over the river Dvina in Vitebsk was strengthened.

STRENGTHENING A ROAD BRIDGE OVER THE RIVER DVINA Some details of reconstruction of the road bridge over the river Dvina in

Vitebsk are given in the November 1970 issue of “Transportnoye Stroitelstvo”. The bridge was erected in 1934. It crosses the main stream of the river in two continuous spans (2 x 63 m) comprising four steel trusses carrying a reinforced concrete deck. During the last war the bridge was partly destroyed and when re-constructed its carrying capacity was limited to 2.5 t. The bridge had to be strengthened.

First proposal for the reconstruction called for a new reinforced concrete deck and for the prestressing of the reinforced steel trusses. The proposed method was rather laborious and a new, cheaper, speedier and more elegant schemes for strengthening the river spans was put forward and found acceptable. The design called for the composite action of the existing concrete deck with steel trusses and for the reduction in dead weight.

The execution was simple. First the wearing surface was removed from the

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deck. Holes were cut next in the concrete deck over panel points in trusses where steel shear connectors were riveted to the top boom to ensure interaction between the truss and the concrete deck.

The next operation was to place eight 200 t hydraulic jacks under each main truss over the central pier and to lift the superstructure 20 cm. To avoid cracking of the concrete, transverse grooves were cut in the deck slab prior to lifting. The raising of the structure resulted in the reversal of stresses in the trusses. The trusses were then reinforced according to the design requirements and in situ concrete was poured into the holes in the deck to bind it with the steel truss. Ex-panding cement was used in the concrete mix.

When the concrete had reached its designed strength the superstructure was lowered and the jacks removed. Calculations showed that about 50% of the working stresses in some truss components were due to the dead load only. To reduce the loading lightweight concrete was used for wearing surface and furt-her reductions in weight were achieved by using asbestos cement pipes for hol-low type deck construction. III. Match the English and the Russian equivalents. Make up sentences with the English words and let your partner translate them.

destroy reduce remove strengthen rivet pour achieve

удалять достигать разрушать приклепывать заливать сокращать усиливать

IV. Fill in the appropriate word from the list below: consists, reduce, between, necessary, filled, avoid 1. The road bridge over the river Dvina in Vitebsk … of two continuous spans. 2. Reconstruction was … to strengthen the structure. 3. Steel shear connectors were used for interaction … the truss and the concrete deck. 4. Transverse grooves were cut in the deck slab to … cracking of the concrete. 5. The holes were … by concrete to bind the deck with the steel truss. 6. To … the loading lightweight concrete was used. V. Analyse the text and determine the main and additional information of each paragraph. VI. Retell the text. Use the answers to the following questions: 1. Why had the road bridge over the river Dvina to be strengthened?

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2. What can you say about the first proposals for the reconstruction? 3. What advantages did a new scheme for strengthening the river spans have? 4. What was the first stage of the reconstruction work? 5. What was done during the next operation? 6. When was the superstructure lowered and the jacks removed? 7. What did calculations show? 8. How was the reduction of the loading achieved?

Home Exercises I. Memorize the words from Ex. I page 86. II. Use this model for compression:

Model: the tubes made of steel – steel tubes The deck made of reinforced concrete; the method which was proposed; the trusses made of reinforced steel; the spans over the river; the bridge that was partly destroyed.

Text 22 I. Scan the text for 10 minutes and choose the answer which you think fits best according to the text. Then read the text carefully and check your ideas. 1. The elegant century old suspension bridge is … a) the Blackfriars Bridge b) the Hampton Court Bridge c) the Hammersmith Bridge 2. The earliest bridge in Great Britain is … a) the Old London Bridge b) the Tower Bridge c) the Albert Bridge 3. The Old London Bridge was of great danger for ... a) pedestrians b) automobiles c) boats 4. The «Lockwood» is a … a) chapel b) viaduct c) ferry 5. Over the Thames there are … a) 26 bridges b) 16 bridges c) 23 bridges 6. The «Britannia» bridge was made of … a) cast iron b) stone c) steel

BRIDGES OF GREAT BRITAIN

There are twenty-six bridges spanning the Thames. The most famous among

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them are: the Tower Bridge erected in 1884 and designed by Sir Horace Jones and Sir John Wolfe Barry, the London Bridge (its medieval predecessor, packed with shops and houses was a virtual village on the river), the Southwark Bridge, the Hungerford Bridge, the Blackfriars Bridge decorated with the finest iron-work and massive supports shaped like pulpits which recall the monks who once lived on the left bank, the Waterloo Bridge commemorating the Duke’s of Wel-lington victory over Napoleon, the Rail and Foot Bridge, the Westminster Bridge opened in 1750 despite protests by watermen fearing competition for their ferries, the Lanberth Bridge, the Vauxhall Bridge sporting statures repre-senting Architecture, Agriculture and Science, the Chelsea Bridge, the Albert Bridge painted in wedding cake colours of rose and pistachio and bearing the order for troops to «break step» when marching across, the Battersea Bridge, the Wandworth Bridge, the Putney Bridge, the elegant century old suspension Hammersmith Bridge, the Chiswick Bridge, the Kew Bridge, the Twickenham Bridge, the Richmond Bridge built in 1774 and widened in 1930 being the oldest still used on the river, the Kingston Bridge and the Hampton Court Bridge. Many bridges have been renovated over the last decade, their designes high-lighted with new coats of paint.

In addition to the above-mentioned passages over the Thames there is the Woolwich Ferry there.

The Old London Bridge is the earliest bridge in Great Britain having the his-torical evidence. Its construction began in 1176 and lasted during 33 years. The outstanding scientist in the field of bridge building Academician G. Perederey who contributed greatly to bridge design in Russia, gave the contemporary as-sessment of the Old London Bridge: «Twenty rather formless piers of different thickness were built at differed intervals from one another on piled grillages which were protected from the scour by the riprap. The spans were not long and some of them were bridged by arches, the other – by beams. The bridge looked as if it were a dam on the river and caused essential drop in water level, which was of great danger for boats. Chapels, shops and many-storied houses were densely built on the bridge. It was always overcrowded...»

From time to time fires broke out in those buildings on the bridge though everything and the bridge itself were made of stone. It’s interesting to note that 650 years later when modern London Bridge was being built to replace the old one, the workers found well-preserved wooden piles under water surface.

Two unique viaducts built in Great Britain in the 19-th century represent the most vivid achievements in world bridge construction. One of them is the «Mouth Water» with supports of 35.4 m high. It was built in 1822 and the other was built in 1848. That structure was called the «Lockwood». Its supports were 36 m high and 1.36 m wide.

The stone bridge «Chester» built in 1834 is well known. Its 61 m long span was claimed as world record for a masonry bridge till 1842.

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The first cast-iron bridge was also built in Great Britain in 1779 to span the Severn at Coalbrookdale. A new page was written in the history of the world bridge erection. The bridge represented a tracery cast iron arch with 30,6 m span. The spandrel was also made of thin cast-iron bar moldings.

And the most celebrated bridge «Britannia» was built in 1850. It was erected for the railway load. The bridge has survived to our days. It is a cast iron con-tinuous box structure (in fact it is a tube). The trains travel through it. The span length strikes even our contemporary engineers – two middle spans are 140 m long each and each land span is 70 m long. The initial design for the «Britannia» bridge was made for a suspension type. The stone towers were erected with the holes for carrying chains. These towers remain as bridge decoration because the continuous beam appeared to be strong enough to carry the necessary load.

The Tower Bridge is a symbol of Great Britain. This unique structure is a combination of a modern steel bridge and a medieval masonry structure. Its towers are built according to a lift type in order to let large ships go under it. This is the only bridge in the world which combines suspension structures with a span lifted vertically with the help of pylons which support carrying chains. II. Match the Russian and the English equivalents.

слой выдающийся проповедники ажурная работа предшественник переполненный формовка

predecessor pulpits coat overcrowded molding tracery outstanding

III. Fill in the missing word. 1. Many bridges in Great Britain were covered with new … of paint. 2. The Tower Bridge is a … of Great Britain. 3. A bridge across the Severn built in 1779 was a … bridge. 4. The Old London Bridge had … piers. 5. The «Britannia» bridge was built for … 6. Along the Old London Bridge there were … and houses. IV. Look at fig. 11, 12. What bridges of Great Britain are represented there? Prove your answer.

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Fig. 11

Fig. 12

V. What bridge of Great Britain is not mentioned in the list below? Can you describe it? the Rail and Foot Bridge; the Chelsea Bridge; the Kew Bridge; the London Bridge; the Battersea Bridge; the Southwark Bridge; the Hungerford Bridge; the Blackfriars Bridge; the Westminster Bridge; the Lanberth Bridge; the «Chester» Bridge; the Vauxhall Bridge; the Albert Bridge; the Wandworth Bridge; the Putney Bridge; the Tower Bridge; the Hammersmith Bridge; the Chiswick Bridge; the Twickenham Bridge; the Waterloo Bridge; the Richmond Bridge; the Kingston Bridge; the Hampton Court Bridge; the «Britannia» Bridge

Home Exercises I. Choose the Russian equivalent. massive – массив, массивный, масса; troop – труп, труппа, отряд; waterman – водяной, водолаз, лодочник; grillage – ростверк, грильяж, рашпер; cast iron – бракованный утюг, сталь, чугун II. You are in Great Britain. Write a letter describing some places of inter-est. Do not forget to mention bridges you like.

Text 23

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I. Read the information and say if the given footbridge can convey traffic and why.

FOOTBRIDGE AT WIESBADEN-SCHIERSTEIN HARBOUR

An interesting structure was built to commemorate the centenary of the Dyckerhoff cement plant in Germany. The footbridge was presented by the Dyckerhoff Co. to the City of Wiesbaden. Located at the entrance of the Rhine Port at Schierstein, the structure is destined to link Biebrich with Niederwailluf, situated on both shores of the river.

The footbridge was built by successive overhangs, using prestressed lightweight concrete, mostly of white colour. The bridge of the arch type; the span between the axis of abutments amounts to 96.40 m, while the rise is of 15 m. Because of heavy river traffic, the bridge was erected without scaffolding or centering, by the cantilever method. The structure was prestressed with Dywidag bars. The overall length referred to above (96.40 m) was divided into three parts: 16.10 m + 64.20 m + 16.10 m. The end parts are of heavy concrete construction, while lightweight concrete was used for central part. This central part constists of 21 voussoirs, which represent a volume of concrete only 180 m3, a rather low figure. It must be noted that high strength cement was used for the central part.

Each work, two voussoirs were concreted by the cantilever method. According to tests carried out by the Dyckerhoff Cement Co., both normal concrete and light concrete showed the same behaviour as regards shrinkage and creep.

An interesting feacher worth mentioning is the use of counterweight approach ramps, providing an original static arrangement and reducing the weight of the foundations, which in this case was a rather expensive item, because of the nature of the soil.

With its length of nearly 100 m and a light concrete zone of some 64 m, the Wiesbaden footbridge was (at the time of its erection) the longest prestressed light concrete footbridge in the world. II. Give Russian equivalents: prestressed lightweight concrete; axis of abutment; scaffolding; cantilever method; heavy concrete construction; high strength cement; counterweight approach ramp. III. Find antonyms to the following words: exit, destroy, light, low, different, cheep, in accordance with. IV. Complete the following sentences using the text. 1. The structure is destined to…

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2. The footbridge was built by… 3. The bridge was erected without… 4. The end parts are… 5. It must be noted that high strength cement… 6. Both normal concrete and light concrete… V. Compare the English sentences with their translations. Is the Russian version correct? 1. The footbridge was presented by the Dyckerhoff Co. 2. The bridge was erected without scaffolding. 3. It must be noted that high strength cement was used for the central part. 4. Both normal concrete and light concrete showed the same behaviour.

a) Пешеходный мост представлял компанию Дайкерхоф. b) Мост возводился без лесов. с) Нужно записать, что высоко-прочный цемент использовался для центральной части. d) И нормальный и светлый бетон вели себя одинаково.

VI. Find in the text ing-forms and define to what parts of speech they belong. VII. Work in pairs. Put 3 questions to every paragraph of the text. Compare your questions with the questions of your partner. Answer the questions you have not got in your list. VIII. Copy and complete the table.

bridge Wiesbaden footbridge material type method of erection lengh

IX. Describe the Footbridge at Weisbaden-Schierstein Harbour.

Text 24 I. Listen and repeat: tier fortify vantage gorge tortuous

[tIq] ['fO:tIfaI] ['va:ntIG] [gO:G] ['tO:Cuqs]

ярус укреплять преимущество узкое ущелье извилистый

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trim spate

[trim] [speIt]

отделывать; зачищать наводнение; паводок

II. Read the text and say if there is a difference between bridge building in France and in Switzerland. Give arguments using sentences from the text.

FRENCH AND SWISS BRIDGES Turning to France, in Provence we find perhaps the greatest Roman work of

all, the famous aqueduct of the Pont du Card, built to carry water to the ancient city of Nemausus, now called Nimes. This is a three-tiered bridge with a total height of more than 160 feet. The lowest tier has six arches, ranging from 50 to 80 feet in span and at this level a modern road has been built alongside, on a bridge of a design, which harmonizes with the Roman work. Because of the widening of the valley the second tier has eleven arches, and as the widest arch in the first tier spans the river, so the widest arch in the second tier is immedi-ately above it. This is the architectural centre of the structure, although not the geometrical centre. The third tier has 35 arches, and is so dimensioned that there are three arches immediately over each lower arch, but exactly four over the wider span.

It is not known who designed the Pont du Card, or when it was built. Au-thorities differ, but the historian M. Menard, believes it was authorized by Agrippa about the year 19 B.C. But old it certainly is, for the water channel along the top is almost blocked up with thick deposits of lime. No water runs through it today, for the watercourse is broken at both ends and the aqueduct leading to the bridge interrupted in many places; all that remains is the bridge itself. The collapse of the Roman Empire led to the Dark Ages in Europe; bar-barianism took over from civilization, communications were severed and the need for bridges and the ability to build them disappeared. No more were seen for several hundred years and the earliest medieval bridge we can find is that over the River Lot at Espalion in France, whose age has been disputed for a very long time, but may be supposed to have been built by Charlemagne about the year 800. It is a bridge of crude workmanship, although strong enough, and marks the emergence of a creative art from the anarchy of barbaric Europe.

As bridges became necessary again for the movement of people, they were also points of weakness in defense, for they afforded easy passage alike to friend and foe. It became the custom to overcome this weakness, at strategic points, by constructing fortified bridges, and while only two of these are to be found in Britain, one at Warkworth in Northumberland, the other at Monmouth, there are many examples on the Continent, particularly in France and Spain. Of these, probably the finest is the Pont Valentre at Cahors in France, built in 1308. It has six arches of about 54 feet span, and although it might look more graceful with one fewer it should be remembered that this was a war bridge, and the pointed

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cutways were carried right up to the roadway to act as vantage points in defend-ing the bridge against boats gathered by the enemy underneath; a narrow arch was easier to defend than a broad one. Furthermore, if as a last resort an arch had to be demolished, the thrust of a wide arch on the unbalanced pier might lead to total collapse of the bridge. In those days bridges had to be built very slowly, and the total ruin of a bridge would have been a major disaster.

Normal civilized life having been resumed; bridges were built everywhere, some great, and some small. Before the arrival of iron and steel there was no al-ternative to masonry but wood, and although wooden beams were sometimes laid on stone piers, for permanence stone was used throughout. Even in modern times it is sometimes desirable, for reasons of good artistic taste, not to use steel where stone will serve, for a stone bridge blends better into the landscape. Swit-zerland is a good example. The Swiss are very clever at building stone bridges, especially in extremely awkward places. Coming down the St. Gotthard Pass, which has been an international highway for hundreds of years, there is a small stone bridge, the Devil’s Bridge, springing from one nearly vertical wall of the gorge to the other. With the passing of time, this bridge became too small and too awkward for the greatly increased traffic using the road, so just above the old one, and still it springs from one wall to the other. When the river is in spate with melting snow, the passage of this gorge is a fearsome business.

Switzerland, being very mountainous, has always presented difficulties for transport. By the accident that the railway was invented long before the motor car, the Swiss, as with other nations, built railways, and had to build them in the face of great natural obstacles. A railway locomotive cannot climb the steep gradients that a motor car can manage with comparative ease, because of the weight of the train and the lack of adhesion between the steel wheels and the steel rails. For very steep climbs the railway engineer has resort to the rack sys-tem, where a pinion on the engine engages with a rack laid between the running rails. This is not a good system for regular traffic, so the ordinary railways have to be laid out with fairly gentle gradients. In mountainous country this is not easy, and spiral curves and unusual bridges are required.

The Albula Railway is one of the most tortuous in Switzerland, because of the difficult country it passes through, and has some intricate tunnels and re-markable bridges. One of the most impressive is the bridge across the Land-wasser gorge which is unusual in several ways. It is built of stone, and its great height of 223 feet above the bottom of the gorge is exceptional. It is built on a curve, whereas bridges are nearly always straight; this was necessary because the take-off and landing points did not face each other. The arches are straight, but are set at an angle to each other on the piers, and the rails are continuously curved, the curvature being quite sharp for a railway, with a radius of only 328 feet. Finally, the bridge ends abruptly against a vertical cliff through which the railway passes into a tunnel.

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The Albula Railway is part of the system called the Rhaetian Railway. The numerous bridges on this, as on the other Swiss railways are always masonry bridges, for the stone was at hand and the method of building stone bridges well understood. But when a new branch of the Rhaetian was constructed in 1914, another technique was adopted for the fine Langwies viaduct, which is of rein-forced concrete.

The great advantage of concrete, or synthetic stone, is that it does not need masons to trim or join it, for the whole bridge is usually one vast solid mass or monolith. Concrete itself has high resistance to compression, but not to shear (sideways thrust) or tension; its strength to these forces is very greatly increased by moulding the liquid concrete round iron or steel reinforcing bars. The strength of this combination is much greater than the strengths of the two mate-rials separately. II. Do the puzzle.

1 c

o

3 4

5

2 o n

s t r u c t i

8

6

9

11 12

10

7

n

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1. a curved structure 2. a layer of matter, often deep under the earth, that has formed naturally 3. to protest from harm 4. pushing something violently 5. a strong material 6. involving the skillful and imaginative use of something 7. a line or surface that bends round 8. all the features of an area that can be seen when looking across it 9. a thing that blocks one’s way 10. to make something smooth by cutting away untidy parts 11. a narrow valley with steep sides usually with a river 12. a drawing III. Cross out the unsuitable word. Give your arguments. The Pont du Card: three-tiered; ancient; fortified; famous; arched; Roman The bridge across the Landwasser gorge: stone; remarkable; Swiss; straight; high; having a cliff as a support IV. Say if the sentences are true, false or not given according to the text. 1. The total height of the Pont du Card is less than 48.8 meters. 2. A good example of reinforced concrete construction is in the new Waterloo Bridge in London. 3. The “white coal” of Switzerland is waterpower. 4. The second tier of the Pont du Card is the geometrical centre. 5. The Pont Valentre in France was a war bridge. 6. Reinforced concrete bridges are found all over the world, but France seems to have a particular genius for this type of construction. 7. First reinforced concrete bridges appeared in Switzerland in 1914. V. Make up questions from the words below and answer them. 1. what / is / of a / the structure / famous / aqueduct / French / Pont du Card of the? 2. who / the designer / the Pont du Card / was / of? 3. what / in Europe / is / the Dark Ages? 4. why / Devil’s Bridge / was / built / a new? 5. why / Landwasser gorge / the / most impressive / is / the bridge / across / the / one?

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VII. Work in pairs. Draw schemes of two bridges from the text and let your partner describe them.

Home Exercises I. Memorize the words from Ex. I page 93. II. Paraphrase the following sentences using there is/there are. 1. You can see a three-tiered bridge in front of you. 2. The third tier has 35 arches. 3. The water channel is blocked up with thick deposits of lime. 4. France has many fortified bridges. 5. Before the arrival of iron and steel the only alternative to masonry was wood. 6. The Devil’s Bridge is situated in the St. Gotthard Pass. 7. Switzerland is very mountainous. 8. The Albula Railway has intricate tunnels and remarkable bridges. III. You are a participant of an International Bridge Congress. Prepare your speech concerning some problems with bridges in your country (France or Switzerland). Then make a list of the problems, discuss them in your group and suggest possible solutions.

Text 25

I. Listen and repeat: vary incline collapse undertake coarse cover rib angle prestressed

['veqrI] [In'klaIn] [kq'lxps] ["Andq'teIk] [kO:s] ['kAvq] [rIb] ['xNgl] ['pri:strest]

изменяться; разниться наклоняться крушение; разрушение предпринимать крупный; грубый; необработанный покрытие; защитный слой ребро; острый край угол предварительно-напряженный

II. Read the text and answer the question “What modern and ancient bridges are there in China?”

ANCIENT AND MODERN CHINESE BRIDGES The art and science of bridge building has been long practiced in China.

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Ancient and modern bridges in this country have much in common. The Anji Bridge in Hebei Province was completed around the year 599, during the Sui Dynasty. It is the oldest surviving open spandrel stone arch bridge in the world. The width of the bridge deck is 10 m. The arch stones are about 1 m thick and 0.25 – 0.4 m wide so that the arched rings vary in width from 9.0 to 9.6 m. Thus, the external rings of the parallel longitudinal arches incline slightly inward, helping to resist collapse.

Between adjacent stones of each arch, two X-shaped iron anchors were placed, about a third of which survived until the mid-1950s, when major repair work was undertaken. It is worth noting that prior to this repair work the Anji Bridge was still open to truck traffic. However, some of the arched rings had collapsed several times during the long history of the bridge.

To consolidate the transverse junction between arched rings, 5 iron bars with capped heads were installed, as was an anchorage bar. A protective layer of fac-ing stones was applied to the upper surface of the main arch. Additionally, 6 L-shaped stones, each 1.8 m long were fitted on each side of the bridge.

The abutments were built up using 5 layers of stone with total thickness of about 1.55 m and a width slightly greater than that of the arch. These stones rest directly on layers of natural coarse sand and are much lighter than normally found in ancient stone bridges.

Some original stones protecting the arches remain in use on side faces. Oth-ers in the middle field of the arch have been replaced by cover slabs made of re-inforced concrete – with toothed connections. Cement mortar was also used, and additional layers of waterproof materials were applied.

After 1949, many open spandrel stone arch bridges were constructed in Chi-na, some with main span lengths of over 100 m, such as the Rainbow Bridge (1961) in Yunnan Province and the Jiuxigou Bridge (1971) in Sichuan Province, These were the longest open spandrel stone arch bridges in the world when they were built. Currently, the longest such span is found on the bridge completed in 1991 across Wuchao River in Hunan Province. This is an arch bridge with two ribs and a clear span of 120 m. Thus, the stone arch open spandrel bridge has continually developed in China throughout the course of history.

Timber cantilever bridges are found throughout China. Because timber beams cannot span long distances, and because of the difficulties in constructing piers in deep valleys and riverbeds in ancient times, the cantilever technique of bridge construction was developed.

According to literary sources, timber cantilever bridges were constructed in China as early as the 2nd century. A 5th century geographical survey “An-notations to River Couige Systems” records a timber cantilever beam bridge with span of more than 13 m in Gansu Province.

The Lu River Bridge in Hunan Province was an 8-span continuous cantile-ver bridge with stone piers and timber beams. The distance centre-to-centre be-

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tween the piers was about 21 m. The span between cantilever ends was about 10 m. This bridge was first constructed in the Southern Song Dynasty (1127-1279), and repaired and reconstructed many times subsequently.

One later repair used 3 long timber beams bound together and connected with iron nails. More than 10 such longitudinal beams were placed at every pier, each with a cantilever of about 1.3 m. On this base, a layer of longitudinal beams followed by another of transverse members were repeatedly piled up to a total of more than 20 layers. Finally, the beams over the cantilevers were erected and inclined timber struts were added later at the 4th layers of timber cantilevers.

Today, the longest continuous box beam bridge in China is the pre-stressed concrete LiUku Bridge over the Nir River in Yuiman Province, completed in 1990 with a maximum span of 154 m. The Second Qiantang River Bridge is a box beam highway bridge constructed parallel to a railway bridge and com-pleted in 1992. Both bridges are continuous, with 18 spans of 45 + 65 +14 x 80 + 65 + 45 = 1340 m without internal expansion joints.

A bridge over the Whitewater River in Gansu Province was first mentioned in literature as early as the Western Jin Dynasty (266-316). At the, end of the 19th century, the Yinping Bridge was reconstructed as a timber cantilever beam bridge and remains in service today. The supports of this bridge are constructed of 10 gradually cantilevered layers of timber, the ends of which are raised to achieve a large angle, of elevation. These cantilevers not only reduce the span of the bridge, but also assume the function of inclined struts.

Cantilevering techniques, with ever larger angles of elevation formed by the overhangs of the piled layers, evolved into timber strut arch bridges using indi-vidual inclined struts. A typical example is the Gannan Bridge in Gansu Prov-ince, a type that serves as a precedent for modern strut-frame bridges.

Two methods for constructing chain suspension bridges are drawn from the Ming Dynasty book, written around 1600. Later in the 17th Century, the Ger-man C. C. Schraman painted the iron chain Yuringn Bridge and attributed it to the 1st century. The suspending chains were joined with the horizontal base chains, so it can be only considered a flexible suspension chain bridge without stiffening girders.

As for chain bridges with stiffening girders no ancient examples survive. Since wood was the only material likely to have been used for stiffening girders, it is difficult to imagine timber girders with very large spans, although middle piers were apparently sometimes employed.

The largest modern suspension bridge in China is the Dazi Bridge in Tibet, with a main span of 500 m. The largest composite cable-stayed bridge of double tower form in China is the Nanpu Bridge in Shanghai, completed in 1991, with a main span of 423 m. At present, several cable-stayed bridges with a main span length of 400 m and more are being constructed in China. These projects include the composite cable-stayed Yangpu Bridge in Shanghai with a main span 602 m

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and other prestressed concrete cable-stayed bridges with main spans exceeding 400 m. All these bridges are for highway use. III. Find 9 pairs of antonyms: IV. Match the beginnings and the endings of the sentences and arrange them in the correct order according to the text. 1. Ancient and modern bridges in China… 2. Open spandrel stone arch bridges were constructed in China… 3. Timber cantilever bridges were constructed in China… 4. The Gannan Bridge is … 5. The Dazi Bridge is … 6. The Nanpu Bridge is … 7. The Ming Dynasty book …

a) … a precedent for modern strut-frame bridges. b) …from the second century. c) …have much in common. d) …after 1949. e) … the largest composite cable-stayed bridge. f) …the largest modern suspension bridge. g) …describes methods for construct-ing chain suspension bridges.

V. Read the text once again and complete the tables (but first copy the ta-bles into your notebook).

The Anji Bridge

location year of construction type bridge deck width arch stones width way of consolidating the transverse junc-tion between arched rings

abutments 5 layers of stone

The LiUku Bridge

location

add; modern; repair; consolidate; develop; ancient; resist; demolish; assist; divide; suddenly; upper; heavy; bottom; light; confine; reduce; gradually

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year of construction type maximum span length number of spans total length

VI. Complete the following sentences by writing no more than three words for each answer: 1. Bridge building in China has a ________ history. 2. In middle of the 20th century ________________ bridges were constructed in China. 3. It was decided to develop the cantilever technique of bridge construction be-cause of some problems connected with ___________________________. 4. Timber strut arch bridges appeared due to _____________________. 5. There were no ancient chain bridges with ______________________ in China. 6. Nowadays in China there are several _______________ and _____________ bridges.

Home Exercises I. Memorize the words from Ex. I page 98. II. Translate from English into Russian. Discuss the translation in your group. 1. Stones protect the arches. 2. He stones cherries. 3. This plant can’t be layered. 4. The abutments consist of 5 layers. 5. Don’t forget to wood. 6. Wood stiffened girders. 7. The road parallels the river. 8. This house is timbered. 9. Timber beams cannot span long distances. 10. He longed to be a chief engineer. III. Get ready to tell a collective story about bridges in China using Ex. VI as a plan.

Text 26

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I. Read the text and define the words in bold.

OUNASJOKI BRIDGE One Finnish periodical gives some details on the Ounasjoki Bridge located

on the highway № 4, at the border of the city of Rovaniemi, which is on the Arctic Circle. It crosses the river Ounas.

The structure is 4 span concrete box girder, prestressed both in longitudinal and transverse directions. Its overall length amounts to 254 m; the two central spans are each 70 m long. Abutments and piers are founded on bored piles.

The bridge was erected according to a cantilever method. The concrete deck was poured in 3.50 m with the aid of a trolley suspended from the cantilever. The choice of the method was influenced by the tight schedule due to climatic factors, giving very little time for the erection of the centering and pouring of concrete. The first end span, followed by a cantilever, 22.75 m long, was poured on forms supported by the scaffolding inside a protective cover. The outside temperatures at that time varied from –20˚ to – 30˚C.

After this stage concreting was continued by the cantilever method. As the length of the cantilever grew, it was suspended by means of cables on mast and by a temporary support until the next pier was reached. The same stages were repeated for each span; and when the opposite shore was reached the trolley was dismantled.

The cantilever method proved quite satisfactory for these arctic conditions. Special precautions were taken to protect concrete against frost such as heating concrete during laying, etc.

The bridge was constructed for the National Road of Public Roads and Wa-terways by A-Betoni Oy Company. II. Translate into Russian. Climatic factors; concrete deck; longitudinal directions; special precautions; central span; outside temperature; transverse direction; temporary support. III. Read the figures and say how they are used in the text.

4 3.5

2 22.75

70 254 30 IV. Work in pairs. Ask and answer the questions. 1. What is overall length of the Ounasjoki Bridge? 2. According to what method was this bridge erected?

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3. Why was this method used? 4. When was the trolley dismantled? V. Work in pairs. Correct your partner according to the model. Model: The Ounasjoki Bridge is located on the highway № 2.

- Oh, no. You are wrong (Nothing of the kind! It’s not true. ). As far as I know, it is located on the highway № 4.

This bridge was erected according to a suspension method. Abutments and piers are founded on box piles. The concrete deck was poured with the aid of a temporary support. The bridge was under construction in summer time. All the spans were erected in a different manner. VI. Fill in the diagram and describe the way of Ounasjoki Bridge construc-tion.

Home Exercises

I. Form the nouns from the verbs and use them in your own sentences. To protect; to erect; to repeat; to heat; to construct; to suspend.

OUNASJOKI BRIDGE

concrete deck _________ first end span pouring

___________ by cantilever method

suspension by ____________

trolley dismantling

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II. Change the following sentences according to the model. Model: It is necessary to examine the accuracy of these results. 1. The progress of the work depends on how efficient the organization is (effi-ciency). 2. The type of pump used will vary according to how much liquid is being pumped (amount). 3. It is necessary to test how much concrete will be consumed (quantity). 4. It is doubtful how accurate the results are (accuracy). 5. It is not clear whether these calculations are correct (accuracy).

Text 27

I. Look through the text and cross out the items which do not fit in the con-tent. Bridge location. Bridge construction. Bridge structure. Way of traffic passing. Replacing the structure. Decision to replace the structure. II. Read the text and check your answers.

A UNIQUE TRANSPORTER HIGHWAY BRIDGE

The city of Duluth, Minnesota, which is situated at the head of Lake Supe-rior, owns and operates a most unique type of highway bridge. The highway connecting Duluth with a strip of land behind which the harbour is located is crossed by the harbour entrance through which a large number of boats passes during the period of the year when the lake is open to navigation.

At the time that the bridge was constructed the highway traffic was rela-tively small and a type of structure was desired so that the shipping would be in-terfered with as little as possible. Such a requirement was found to be met by the transporter type of structure, this type of bridge consisting of an overhead frame of steelwork upon which a carriage moves back and forth.

Shipping is therefore free to pass at all times without it being necessary to open the bridge as would be the case if a movable span structure had been used. Highway traffic consisting of foot passengers or vehicles is loaded on the car-riage on one side of the Channel and carriages propelled by electric motors moves to the other side and the vehicles unloaded.

For a number of years this bridge has served very satisfactorily but recently

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the highway traffic has increased so much that vehicles are delayed and have to wait in line for their turn to be carried across. So the city has deemed it neces-sary to replace this structure with one of the ordinary type of movable spans so that vehicles traffic will be served with less inconvenience. This transporter type of bridge is used rather extensively in Europe but the structure in Duluth holds the distinction of being the only one of its kind serving highway traffic in the United States. III. What notion is described? - an area of water protected from the open sea by land or walls, in which ships can shelter; - a large vehicle used for carrying heavy objects; - to change position; - a time when each member of a group must or may do something; - movement of ships over water IV. Complete the sentences. 1. A unique type of highway bridge is situated … 2. The transporter type of structure was chosen because… 3. Passengers and vehicles were carried by… 4. Because of highway traffic increase… 5. This transporter type of bridge is the only in… V. Match the town and the bridge situated in it. Can you describe each of them in 2 – 3 sentences?

Moscow the Egyptian Bridge Omsk a transporter bridge Novosibirsk the Rail and Foot Bridge Hebei Province, China the Irtysh River Bridge Nimes, France the Lefortovsky Bridge Duluth the Anji Bridge St. Petersburg the Pont du Card London the Dimitrov Bridge

Text 28

I. Match the Russian and the English equivalents. Use the English words in the sentences of your own.

повторение место полый

accommodation repetition craft

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судно топить берег риск

hazard shore hollow sink

II. Read the text and express the main idea.

BRIDGING THE CHANNEL The type of the bridge proposed for the Channel crossing with accommoda-

tion for road and rail traffic would consist of a long series of standard repetition spans of about 740 feet, each on concrete supporting piers and with such longer spans, at intervals, as may be required for navigation of larger craft. Some 800.000 tons of structural steel would be necessary for the superstructure of such a bridge.

The construction of a bridge of such a size and type presents problems and opportunities quite different from those encountered in normal structures. Its construction requires the fullest adoption of mass production methods at all stages of work.

The principle construction hazard of a Channel bridge lies in the prevailing weather conditions. These invite a scheme with the highest possible degree of preassembly on shore and the minimum of work on the actual site of the bridge.

The concrete piers on which the bridge spans would rest must be prefabri-cated on shore in large hollow sections, launched and floated to their permanent sites where they can be sunk into position with the aid of equipment on mobile working platforms. III. Complete the sentences using the text. 1. The bridge for the Channel would consist of… 2. For the superstructure of such a bridge it would be necessary… 3. The construction of the bridge requires… 4. The concrete piers must be… IV. Answer the questions. 1. What is the type of the bridge proposed for the Channel? 2. For what purpose do we need long spans? 3. For what part of the bridge would some 800.000 tons of structural steel be necessary? 4. What methods are necessary for the construction of this bridge? 5. Where must the concrete piers be prefabricated?

Home Exercises

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I. Copy and complete the table. Can you find the infinitives and participles below in the text? Be attentive answering the question.

Infinitive Participle I Participle II … crossing …

support … … require … …

… prevailing … … … floated

II. Find the corresponding Participles to the nouns and make up sentences with the completed phrases.

the result the student the railway the countries the methods the car the film the research the workers

developed developing the speed of 80 km/h attending all the lectures made in the laboratory built between the two towns shown to the students building a new house offered by the young specialists achieved

III. Write the summary of the text.

Text 29

I. Listen and repeat: surveillance lengthman gang overhaul assess debacle displacement deteriorate seam shrinkage cavity harden

[sq'veIlqns] ['leNTmxn] [gxN] ['quvqhO:l] [q'sqs] [deI'ba:kl] [dIs'pleIsmqnt] [dI'tIqrIqreIt] [si:m] ['SrINkIG] ['kxvqtI] ['ha:dn]

наблюдение обходчик, дорожный мастер бригада тщательный осмотр; капи-тальный ремонт оценивать ледоход смещение; перемещение ухудшаться; разрушаться шов; спай усадка полость, пустота делать твердым; укреплять

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II. What is the best way to preserve a bridge in its original condition? Read the text and make a list of words connected with bridge maintenance.

BRIDGE MAINTENANCE

After a bridge has been built it is put into a permanent operation. The State Acceptance Committee provides the final accept and studies the construction documents, examines the bridge involving the geodetic devices for more thor-oughly inspection. Every structure is tested to locate defects before they become serious.

The testing is carried out under static and dynamic overloading of building components in order to find out how the bridge is supposed to accommodate the design load on different elements and joints, which can change their initial posi-tions.

In case the structure meets the standard requirements and the acceptance documents are signed, the bridge is transferred to the possession of the railway and motorway maintenance sections.

The Building Code containing the rules and demands for current mainte-nance of the constructional works must be observed to provide safe and reliable operation during the design life for 80 – 100 years. All necessary surveillance and in-depth bridge inspection for long bridges is carried out by a bridge fore-man. Short bridges and culverts are inspected by a road lengthman. They head the gangs which permanently provide structural inspection of the bridges and culverts to locate the damages and defects; repair small damages and defects; clean the bridge from snow, slush and mud; determine the wear-and-tear stage of the bridge elements draw up the service forms and records for bridge inspec-tion and testing; execute records in case the bridge needs reconditioning or overhaul.

There are four assessment stages of a bridge state: «zero stage» for the normal bridge state, «the first stage» in case of small faults and troubles which could be repaired

while reconditioning, «the second stage» when the bridge needs an overhaul, «the third stage» when the bridge is subject to reconstruction or must be re-

placed. The bridge carrying capacity is of great importance for the maintenance of

the structure. The fact is that at present many railway and motorway bridges in Russia are designed and erected according to the Building Code and engineering specifications issued between 1884 and 1985.

On the other hand the modern Building Code issued in 1985 allows the live load, which might be applied in 80 or 100 years. But at present the value of the acting live load is considerable less. That is why specialists assess the bridge carrying capacity according to the classification of the superstructure elements

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and to the classification of the live load. When compared, these two values al-low to make a conclusion on the scope of the bridge operation efficiency under the modern load.

Every bridge type has its own peculiarities and due attention must be given to them from the point of view of operation and maintenance.

For timber bridges one of the most urgent problems to be solved is the deba-cle and high-flood in case of short spans bridges (between 2 and 6 m).

The ground hollowed out by the rushing waters may cause the support slip or displacement. In addition timber can deteriorate and decay and as a result some bridge elements may be worn out. And besides, timber structures suffer from fire.

Metal structures also demand the appropriate care because their elements and joints fail by corrosion. That is why metal bridges need painting and stainless steel is too expensive. The high-strength bolts and rivets slackening call for permanent and qualified inspection as well as the breakage of the welded seams.

The reinforced concrete bridges do not require heavy maintenance cost when they are erected without any technological violation. But fractures and cracks, concrete chips and reinforcement corrosion, holes and shrinkage cavities might frequently occur and present most dangerous defects especially for the bridge supports of reinforced concrete. The bug holes may appear when concrete hardens. In addition the displacements and shifts of the supports occur if the soil is not hard enough.

Culverts need careful inspection and cleaning from mud before every high flood. Some culvert sections might be displaced by the uneven settlement of the embankment. III. Choose the Russian translation for the English word(s). Give your ar-guments. a) a building – строящийся; здание; строительство b) to subject – к предмету; подвергать; субъект c) according – аккордеон; созвучный; согласно d) value – ценность; оценщик; ценный e) care – каре; забота; держатель f) geodetic – геодезический; геодетический; географический

IV. Make up beginnings of sentences and try to complete them. A bridge Damages Timber Metal Specialists

must be

can must

tested… burn…

erected… inspect…

examined… clean…

crack… wear out…

located… rust…

repaired… survey…

decay…

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V. Complete the chart. What process is described?

VI. Retell the text using the list of words you have made up according to Ex. II.

Home Exercises I. Memorize the words from Ex. I page 108. II. Change the Voice of the sentence. 1. The State Acceptance Committee studies the construction documents. 2. Bridge foremen carry out all necessary surveillance. 3. Culverts and short bridges are inspected by a road lengthman. 4. Builders must pay due attention to peculiarities of every bridge type. 5. Specialists test bridges to locate defects. III. Copy the table and fill it in.

timber bridges

metal bridges

reinforced concrete bridges

culverts

factors which can cause destruction

debacle; high-flood; decay; …

Text 30

static and dynamic ____________

transferring to railway and motorway _____________sections

bridge foreman or road lenghman inspection

small defects ___________

cleaning

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I. Listen and repeat: workmanship rebar stress corrosion prestressing steel state-of-the-art composite strain adhesive tendon unidirectional alkaline strap laminate lamina tensile

['wq:kmqnSIp] ['ri:ba:] ['stres kq'rquZn] ['pri:strqsIN 'sti:l] ["steItqvTi'a:t] ['kOmpqzIt] [streIn] [qd'hi:sIv] ['tendqn] ["ju:nIdI'rekSqnql] ['xlkqlaIn] [strxp] ['lxmIneIt] ['lxmInq] ['tensaIl]

профессиональное мас-терство, квалификация арматурный пруток коррозия под напряжени-ем напрягаемая арматура достигнутый, внедренный композиционный матери-ал напряжение клейкий, связывающий предварительно- напря-женная арматура однонаправленный щелочной лента слоистый материал; рас-слаиваться тонкий слой; тонкая пла-стина растяжимый

II. Read the information about composite materials in bridge repair in or-der to get the main idea.

COMPOSITE MATERIALS IN BRIDGE REPAIR It is frequently necessary to strengthen existing bridges or parts of them. The

reasons that make this sort of reinforcement necessary can be summarised as fol-lows:

First, a change in the use of a bridge may produce internal forces in individ-ual structural parts that exceed the existing cross-sectional strengths. These in-creased internal forces may be a result of higher loading or a less favourable configuration of an existing loading. Bridges may also need reinforcement be-cause damage due to external factors has reduced the cross-sectional resistance. The object of repairing such damage is to restore the original cross-sectional strength. Another possibility is misdesign of a bridge or parts of it. This includes all cases where the cross-sectional strength at crucial points is too low so that either the cross-sectional safety or the overall safety of the respective structure or structural element fails to comply with existing codes. Poor construction workmanship may mean that the cross-sectional strengths originally calculated are not achieved. For instance, the as-built cross-sectional dimensions may be smaller than those planned. Or it can happen that individual rebars or tensioning

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cables are incorrectly set, interchanged or even missing, which reduces the cross-sectional strength substantially.

Another severe problem is stress corrosion of prestressing steel. Even today it is not possible to rule out damage of this kind notwithstanding the great im-provements made in the properties of prestressing steel. Many hundreds of thou-sands of bridges worldwide will need to be repaired within the next few years for one or other of these reasons.

There are a number of ways to repair a particular bridge or parts of one, de-pending on the type of construction and the given situation. Adhesively bonded external steel reinforcement is one possible way of achieving structural strength-ening. This method was originally invented in France in the mid sixties; in the early seventies it was further developed in Switzerland, Germany and England and is nowadays state-of-the-art in Western Europe. Advanced composite strips or sheets can replace steel plates (which were used for post-strengthening). They do not corrode; they are easy to handle on the construction site and can be lifted onto the structure with a scissors-lift or similar device without expensive scaf-folding; they are simply rolled on like "wallpaper"; the strips are available on endless reels, so no joints are necessary; they increase flexural and shear strength and reduce deflections and cracking; they cause minimal disruption to the bridge function; they require less time and labour to install; costs are lower than for other methods such as external post-tensioning.

From 1982, carbon fibre reinforced epoxy resin composites have been suc-cessfully employed for the post-strengthening of reinforced concrete beams. Loading tests were performed on more than 90 flexural beams having spans of between 2 and 7 metres. The research work shows the validity of the strain compatibility method in the analysis of various cross-sections. This implies that the calculation of flexure in reinforced concrete elements which are post-strengthened with carbon fibre reinforced epoxy resin composites can be per-formed in a similar way to that for conventional reinforced concrete elements. The work also shows that the possible occurrence of shear cracks may lead to peeling of the strengthening composite. Thus, the shear crack development represents a design criterion. Flexural cracks are spanned by the CFRP strip and do not influence the loading capacity. In comparison to the unstrengthened beams, the strengthening strips lead to a much finer cracking distribution. A cal-culation model developed from the CFRP (carbon fibre-reinforced plastic) com-posite agrees well with the experimental results.

When a change of temperature takes place, the differences in the coefficient of thermal expansion of concrete and the carbon fibre reinforced epoxy resin composites result in thermal stresses at the joints between the two components. No negative influence on the loading capacity of the three post-strengthened beams was found after 100 frost cycles ranging from +20-deg C to —25-deg C.

Highly filled epoxy resin is the classic adhesive for bonding. The adhesive

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must be applied to the CFRP strips in a roof shape so that the extra adhesive is squeezed out when the strip is pressed to the concrete structure. For a strip width of 140 mm, for example, the peak height in the middle of the strips is about 7 mm. Uniform pressing of the CFRP strips and evacuation of entrapped air can be achieved through the use of a hard-rubber roller. Excess adhesive can then be removed and the CFRP cleaned, if necessary. If required for aesthetic reasons, the outer face of the CFRP strips can be coated with epoxy paint. Cement mor-tars can also be applied after the reinforcement has been primed with a suitable bonding agent. Post-strengthening with strips is best suited for more or less flat girders and slabs. For a 1 mm thick strip, a minimum radius of curvature of approx. 300 mm is required. This method, therefore, cannot be used for wrap-ping of columns with a rectangular cross section.

Another important method for rehabilitation is external post-tensioning. This method whereby the steel tendons are not embedded in the concrete, but are placed instead “externally” to the structural elements, offers the advantage that the tendons can be inspected and replaced. However, this normally rules out grouting of the steel tendons, thus making them susceptible to corrosion. Stress corrosion is another problem for the highly tensioned steel cables.

So, it was decided to use composite materials as an alternative to steel. Ad-vanced fibrous composites offer the engineer in the construction industry an out-standing combination of properties not available from other materials. Fibres such as glass or carbon can be introduced in a certain position, volume fraction, and direction in the matrix to obtain maximum efficiency. Other advantages of-fered by advanced composites are lightness and resistance to corrosion and stress corrosion. Some also offer outstanding fatigue performance and greater efficiency in construction compared with more conventional materials.

The question of which fibre is most suitable is still the subject of lengthy discussions. A careful evaluation showed that, in most cases, carbon fibre is the material best suited for bridge repair. This fibre is alkaline-resistant and does not suffer stress corrosion. These are very important arguments for such applica-tions.

Single FRP wires or strands have been used for external post-tensioning for some years. Larger units of parallel wire or strand bundles have been rarely used in the past but two such applications were realised in 1998.

A pin-loaded strap element may provide a practical means. This element consists of a unidirectional FRP lamina wound around endpins in a racetrack manner. No machining of holes is required. The layers in the composite are cured to produce a solid laminate. Circular pins transfer the tensile load to the components being joined. Such straps have many desirable characteristics, in-cluding high tensile load capacity, low weight, low thermal conductivity and low thermal expansion. As a result, laminated pin-loaded straps have been used in many different structural applications, such as temporary bridges. They are

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ideally suited for bridge repair due to the very simple loading technique with pins. However, both experimental and theoretical studies have revealed “high” stress concentrations next to where the strap leaves the pin. The effect of these concentrations is to considerably reduce the load at failure compared to that of the straight solid laminate, as determined by a standard coupon test.

One means of reducing these undesirable stress concentrations is to replace the solid laminate by the non-laminated equivalent. In the "new" strap, there are a number of non-laminated layers formed from a single, continuous, thin ther-moplastic. This type enables the individual layers to move relative to each other. The undesirable stress concentrations are therefore reduced because this struc-tural form has inner shear stress concentrations to be reduced in order to achieve a uniform direct strain distribution in all layers through the thickness.

Apart from improving stress distribution, winding can easily be performed on of the components to be connected. The cost effectiveness of the non-laminated strap is also superior to the laminated strap because the consolidation process is not required.

This system could have an excellent future in bridge repair. There is a high probability that "non-laminated FRP straps" will be as strong as cables for ex-ternal post-tensioning, and much cheaper.

III. Match the words.

existing external bond disruption compatibility occurrence mortar susceptible fatigue conventional means

разрушение существующий обычный чувствительный внешний соединение средство совместимость раствор распространение усталость (металлов)

IV. Look through the text once again and complete the following sentences. 1. Bridges may need reinforcement because of a change in … and … due to ex-ternal factor. 2. Another reason making reinforcement necessary is … of a bridge or its parts. 3. There is another severe problem – … of prestressing steel. 4. The way of achieving structural strengthening is using adhesively bonded ex-ternal steel … 5. From 1982 … have been successfully employed for the post-strengthening of reinforced concrete beams.

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6. The classic adhesive for bonding is … 7. Post-strengthening with strips is best suited for … 8. Another important method for rehabilitation is … 9. For external post-tensioning instead of steel … was used. 10. Non-laminated fibre-reinforced plastic … have an excellent future. V. Write down a plan of the text and let your partner explain each item. VI. Work in groups. Read the information of how the discussed composed materials are used in bridge repairing. Write out the key phrases on the blackboard and retell your piece of information in Russian (one example is for one group).

1. This bridge, located in the Canton of Lucerne, was completed in 1969. In 1991, it needed repairing. The bridge was designed as a continuous, multispan box beam with a total length of 228 m. The damaged span of the bridge had a length of 39 m. The box section is 16 meters wide, with a central, longitudinal web. During core borings performed to install new traffic signals, a post-tensioning tendon in the outer web was accidentally damaged with several of its wires completely severed by an oxygen lance. As a result, the granting of au-thorisations for special, heavy loads across the bridge was suspended until after completion of the repair work. Since the damaged span crosses Swiss National Highway A2, the traffic lanes in the direction of Lucerne on this highway had to be closed during the repair work. The work could therefore only be conducted at night. Carbon fibre-reinforced plastics (CFRPs) are forty to fifty times more ex-pensive per kilogram than the steel used to this date (Fe 360) for the reinforce-ment of existing structures. Do the unquestionably superior properties of CFRPs justify their high price? When one considers that, for the repair of the Ibach Bridge, 175 kg of steel could be replaced by a mere 6.2 kg of CFRP, the high price no longer seems so excessive. Furthermore, all the work could be carried out from a mobile platform, thus eliminating the need for expensive scaffolding. The bridge was repaired in 1991 with three CFRP strips of 5000 mm length. The properties of these strips are given in Table I, strip type No. 3. A loading test with an 84-tonne vehicle demonstrated that the reinstatement work with the CFRP strips was a complete success. The experts working on the repair of the Ibach Bridge were pleasantly surprised at the simplicity of applying the 2 mm thick and 150 mm wide CFRP strips. This was the first repair of a bridge with externally bonded CFRP strips in the world. Since 1991, this application has en-joyed success exceeding all expectations.

2. The covered wooden bridge near Sins in Switzerland was built in 1807 to

the design of Josef Ritter of Lucerne. The original supporting structure on the western side is almost completely preserved to this day. The eastern side was

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blown up for strategic reasons on November 10, 1847 during the civil war. In 1852, the destroyed half of the bridge was rebuilt with a modified supporting structure. On the western side, the supporting structure consists of arches strengthened with suspended and trussed members. On the eastern side, the sup-porting structure is made up of a combination of suspended and trussed mem-bers with interlocking tensioning transoms. Originally, the bridge was designed for horse-drawn vehicles. Since the thirties, vehicles with a load of 20 tonnes have been permitted. In 1992, the wooden bridge was in urgent need of repair. It was decided to replace the old wooden pavement with 20 cm thick bonded wooden planks, transversely pre-stressed. The most highly loaded crossbeams were strengthened by EMPA (EMPA is the German acronym for Swiss Federal Laboratories for Materials Testing and Research) using carbon fibre-reinforced epoxy strips. Each of these crossbeams was constructed of two solid oak beams placed one upon the other. In order to increase the depth, wooden blocks were originally inserted between the beams. The lower beams were 37 cm deep and 30 cm wide; the upper beams 30 cm deep and 30 cm wide. The crossbeams were strengthened either with 1.0 mm thick CFRP strips made of high-modulus M46J fibres or with 1.0 mm thick CFRP strips made of high-strength T700 fibres. The M46J strips were 250 mm wide at the top and 200 mm wide at the bottom. The T700 strips were 300 mm wide at the top and 200 mm wide at the bottom. Be-fore bonding the strips, the bonding surface was planed with a portable system. Selected crossbeams are equipped with strain measurement devices, which allow long-time monitoring. Up to now, the results are very satisfactory. After applica-tion of the CFRP strips pulse infrared thermography was applied very success-fully for the first time for quality assurance of the bonding. The historic wooden bridge in Sins is a valuable structure, both from the aesthetic and from the tech-nical viewpoint. It is also of historic value and under protection as a national monument. The technique using CFRP strips is especially suited for post-strengthening structures such as this since the thin but extremely stiff and strong strips are hardy noticeable and therefore do not detract from the original design of the structure. Since 1992, the strengthened crossbeams of the Sins bridge with CFRP-strip reinforcement have helped to provide practical experience under ex-tremely high loading and built up confidence in this technique for preserving historic bridges. Meanwhile, many similar structures have been rehabilitated in this manner in Europe and in North America.

3. Rehabilitation of the Oberriet-Meiningen Bridge was planned in late

1996. The bridge, built in 1963, spans the border between Switzerland and Aus-tria, linking Oberriet to Meiningen. It crosses the River Rhine in three spans (35-45-35 m) as a continuous steel/concrete composite girder. Due to increased traf-fic loads, post-strengthening of the concrete bridge deck became necessary. The application of a total length of 640 m of CFRP strips has proved extremely suc-

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cessful. Thorough investigations have shown that beside routine maintenance the concrete bridge deck was also in need of transversal strengthening. This was obviously due to the fact that the deck was designed in 1963 for the then stan-dard truckload of 14 tons. Today, the standard truckload for this type of bridge is 28 tons.

Because the existing concrete was in good condition and the chloride con-centration in the concrete exceeded the critical values only in the outermost 10 mm it was decided not to replace the deck. Simply increasing the depth of the deck by adding concrete to attain the necessary transversal flexural capacity, would, however, have caused inadmissible longitudinal stresses for the super-structure. Bonding of additional reinforcements therefore remained the only so-lution. Structural components post-strengthened with bonded plates or strips were to have a total residual safety factor of 1.2 after failure of the plates or strips. The fact that the required strengthening factor was 2.15 meant that the sectional area of the deck slab still had to be increased. Bonding transversal CFRP strips on the bottom of the slab and adding 8 cm of concrete on top of the slab made it possible to meet all requirements. Adding new concrete also al-lowed removal of the top layer of concrete with the high chloride concentration by water blasting. CFRP strips 80 mm wide and 1.2 mm thick (70 vol% T700 fibres, strength 3000 MPa) were chosen for post-strengthening. A total of 160 strips, each 4 m long, were laterally bonded to the bridge deck every 75 cm.

4. This bicycle and pedestrian bridge over the river "Kleine Emme" near Lu-

cerne was post-tensioned with 2 CFRP cables in October 1998. The bridge is 3.8 m wide, 47 m long and is designed for the maximum load of emergency vehi-cles. The superstructure is a space truss of steel pipes in composite action with steel post-tensioned with two CFRP cables inside the tube. Each cable was built up with 91 pultruded CFRP wires of 5 mm diameter. The post-tensioning force of each cable is 2.4 MN. Therefore, the CFRP wires are loaded with a sustained stress of 1350 MPa. Each cable is equipped with three CFRP wires with an inte-grated the pultrusion process. In the post-tensioning phase it was possible to cal-culate the post-tensioning force at all times from the data of the wires with cali-brated sensors. Monitoring has continued since then and up to now no relaxation has been observed.

5. The "Verdasio" bridge is a two-lane highway bridge and was built in the

seventies. The length of the continuous two-span girder is 69 m. A large internal prestressing steel cable positioned in a concrete web corroded as a result of the use of salt for de-icing. It was replaced in December 1998 by four external CFRP tendons arranged in a polygonal layout at the inner face of the affected web inside of the box. Each cable was made up of 19 pultruded CFRP wires with a diameter of 5 mm. Here too the cables are equipped with sensors to

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measure the post-tensioning force. VII. Match the given words with their common and special meanings (con-sult the dictionary). In what meaning are these words used in Ex. VI?

Common meaning Special meaning case bond plate scaffold lead face cure stress

1) тарелка 2) эшафот 3) приводить 4) связывать 5) лицо 6) вылечивать 7) случай 8) подчеркивать

a) подмости b) выпускать облигации c) целиться в летящую птицу d) коробка e) поверхность; торец f) выдерживать g) подвергать напряжению h) полоса (металла)

VIII. Put the following sentences in the correct order to know the process of flexible fabrics application.

Application of sheets (flexible fabrics) would normally require the following steps: - Remove dirt from concrete surface, round off sharp corners (minimum radius should be in the order of 25-30 mm). - Apply putty after the primer becomes tack free. After putty application, al-lowable unevenness must be in the order of 1 mm. - Primer coating, putty application (optional). - Mix the epoxy resin and apply it on the concrete surface (undercoating). - Adhere the fabric. - Blow or sweep dust off the concrete surface after sandblasting or grinding, dry the concrete (if wet). - Press using a roller, allow for complete fabric impregnation and apply an-other coating. - Protect reinforcement from rain, sand and dust; apply paint (if needed) once the resin is tack free. - Remove residual resin using a rubber scraper.

Post-strengthening with sheets is best suited for wrapping of columns with a rectangular cross-section. A minimum radius of curvature of approx. 25 mm is required.

Home Exercises I. Memorize the words from Ex. I page 111. II. Advertise any composite material you have read about.

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Text 31

I. Try to translate the following word combinations which are made accord-ing to N + N model. world obstacles; sea currents; boundary dimensions; seabed silt; maintenance costs; bridge supports; weather conditions; railway tunnel; travel time II. Look at the title of the text. What do you think it is about? Say words you expect to find in the text. III. Now read the text, check your guesses.

BRIDGE OR TUNNEL

The vast water areas all over the world represent the world obstacles for people’s communication. A man has been striving to subdue water spaces by means of the main road connecting continents, islands, etc. because the economy becomes globolised.

The English Channel separating Great Britain and Europe the Straits of Gi-braltar between Europe and Africa, the Bosporus between Europe and Asia, the Bering Strait connecting the Eurasian and American continents, Japanese-islands might offer the missing link for rapid increase land-based transportation to promote improved trade and commerce to facilitate greater economic integra-tion.

Builders always have the choice between bridging and tunneling in crossing over or under a large waterway. Each sort of a structure offers its advantages and shortcomings. One should bear in mind the influence of strong sea currents, great water depth, and large capacity vessels with great boundary dimensions (the under clearance of the bridges must be about 65 m high not to prevent ship-ping), complicated geological seabed structure. Seabed silt is a rather soft foun-dation for supports footing. In addition these regions are seismically dangerous and constructional works must provide sufficient strength against seismic waves.

The advantages of the bridge crossing may be the following: 1. Low cost of construction in comparison with a tunnel structure though

sometimes it may be quite the opposite. 2. Bridges require lower maintenance costs because tunnels call outlays for

water discharging, ventilation, illumination, etc. The longer subaquatic structure is, the heavier outlays are required.

The advantages of the tunnel are: 1. Free shipping is very important under intensive navigation. Tunnels are

much safer as compared to the bridge crossing because bridge supports must be

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calculated for the berthing impact. Being deep beneath the water surface, tunnels do not interfere with navigation. In addition, weather conditions cannot influ-ence the traffic.

2. The architectural view of the tunnel is more attractive because there is no need for high approach embankments.

The final decision for choosing a bridge or a tunnel depends on many factors and not only on technical ones. In some cases bridges are much more preferable. In 1974 the bridge across the Bosporus was erected. In 1985 the bridge crossings connected some Japan islands.

The strait separating Denmark and Europe was also spanned by a bridge. But the choice fell on a tunnel underneath the English Channel. In 1994 the

railway tunnel from Great Britain to France was put into operation. It provides a high-speed rail link with shuttle trains reducing the travel time between the two countries to three-and-a-half hours. Needless to say that the cost of this tunnel is enormous. Another group of Japanese-islands were also connected by the tun-nels in 1987.

The problem «a bridge or a tunnel» is being discussed for the type of struc-tures in the nearest future in Italy and across the Straits of Gibraltar and the Ber-ing Strait. The choice falls on a bridge crossing in Europe and on a tunnel for the severe northern conditions. IV. Fill in the most suitable word. 1. There always was a choice between bridging and tunneling in … over or un-der a large waterway. a) crossing b) crippling c) cruising 2. Bridges require lower maintenance … than tunnels. a) corrosion b) corrugations c) costs 3. Tunnels are much … as compared to the bridge crossing. a) saving b) saver c) safer 4. Weather conditions cannot influence the … through tunnels. a) traffic b) transfer c) transit 5. The cost of the tunnel under the English … is enormous. a) Cheddar b) Channel c) Canal V. Read the text once again and find the word that means the opposite of the word given.

gathering _________________ slow _________________ drawback_________________ allow_________________

bound (adj.) _________________ lessening _________________ small_________________ shallow _________________

VI. Mark these sentences true, false or not given. 1. ______ The Straits of Gibraltar separates Europe from Africa.

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2. ______ The under clearance of the bridges must be over 60 m high not to prevent shipping. 3. ______ For the first time the Bosporus was bridged in 1973. 4. ______ Tunnels require lower maintenance costs. 5. ______ Vessels can navigate much easier if there are no bridges. 6. ______ The Bosporus bridge managed to withstand the wind blows up to 162 km per hour. VII. Copy the table and complete it using the information from the text and your own knowledge.

bridge tunnel advantages

disadvantages

Home Exercises I. Paraphrase the following sentences. 1. The vast water areas all over the world prevent people’s communication. 2. Choosing between bridging or tunneling one should bear in mind many fac-tors. 3. Tunnels are much safer than bridges. 4. The cost of the railway tunnel from Great Britain to France was enormous. 5. The English Channel separates Great Britain and Europe. 6. Every structure offers its advantages and disadvantages. II. Retell the text using the phrases below for help. The text is about...; the text deals with the problem of...; it should be noted that...; in comparison with …; it is worth mentioning...; I know that...

Text 32

I. Listen and repeat: immersed tube riverbed exceed

[I'mq:st 'tju:b] ['rIvqbed]

опускная секция (подводного тоннеля) русло реки превышать, превосходить

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utility deal submarine bore shield horseshoe

[Ik'si:d] [ju'tIlqtI] [di:l] ['sAbmqri:n] [bO:] [Si:ld] ['hO:sSu:]

связанный с коммунальными услугами общаться, иметь дело подводный сверлить, бурить щит подкова

II. Do you remember bridges classification? Enumerate types of bridges you know. III. Read about various types of tunnels. Compare indications of tunnels and bridges classification. Are they similar or different?

TUNNELS CLASSIFICATION

Tunnels are underground constructional works driven for transportation pur-poses including such uses as railroad, rapid transit, highway, pedestrian pas-sages, sewerage, water supply, water power, public utility and canal. There are also immersed tubes. The pipes of great length are laid into a trench in the sea or riverbed and jointed under water. The tunnel length considerably exceeds its cross section. Tunnels are the most complicated engineering works and call for great expenses.

Tunnels classification as well as bridges classification involves several indi-cations.

Indication 1 – by the tunnel function. 1.1. Traffic tunnels. (Much attention will be paid to this kind of tunnel works). 1.2. Mine tunnels. (For mining mineral resources). 1.3. Public utility tunnels. (For public utilities in large cities – water supply and sewerage, electric- and telecables). 1.4. Water power or hydraulic tunnels. (For water supply and water discharge). 1.5. Special-purpose tunnels. (For increasing the country defensive capacity).

Let’s pay due attention to the traffic tunnels because the students of the «Bridges and Transport Tunnels» faculty deal with these type of tunnel works. The traffic tunnels may be classified as following:

Indication 1.1 – by the tunnel function. 1.1.1. Railway tunnels. 1.1.2. Motor way tunnels. 1.1.3. Pedestrian tunnels. 1.1.4. Metro tunnels. 1.1.5. Shipping tunnels.

Indication 2 – by the tunnel location. 2.1. Plain tunnels.

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2.2. Mountain tunnels. 2.3. Submarine tunnels.

The Mersey Tunnel in Great Britain belongs to the longest submarine tun-nels and links Liverpool and Birkenhead. The workers began tunneling from the both banks of the river and the breakthrough took place in the middle of the river beneath the riverbed.

Submarine tunnels can be bored through the rock or sometimes they appear to be huge metal tubes resting on the riverbed and having their portals on the opposite banks of the water obstacle.

There are several tunnels beneath the Thames in London which provide railway and foot passages under water. The twin tunnels the Blackwall Tunnel (Southbound) and the Blackwall Tunnel (Northbound), the Greenwich Foot Tunnel and the Rotherhithe Tunnel link the motor ways of the both banks.

Indication 3 – by the construction method. 3.1. Tunnels built by the cut-and-cover method. 3.2. Tunnels built by cutting technique or rock tunnels. 3.3. Shield driven tunnels.

Indication 4 – by the tunnel depth. 4.1. The shallow tunnels (up to 10 m deep). 4.2. The deep tunnels (over 10 m deep).

Indication 5 – by the shape of the tunnel cross section. 5.1. Tunnels of a rectangular cross section. 5.2. Tunnels of a circular cross section. 5.3. Tunnels of a horseshoe shape cross section.

III. Match the English and the Russian equivalents. pedestrian tunnel highway tunnel shield driven tunnel mine tunnel cut-and-cover tunnel

пешеходный тоннель тоннель, сооружаемый щитовым способом тоннель, сооружаемый открытым способом автодорожный тоннель горнопромышленный тоннель

IV. Use the words in the list to write the opposite of the phrases below. plain, rock, shallow, above-ground, pedestrian, circular

1 deep tunnel ≠ 2 traffic tunnel ≠ 3 rectangular tunnel ≠

4 mountain tunnel ≠ 5 cut-and-cover tunnel ≠ 6 underground works ≠

What indication do the tunnels from 1 – 5 refer to? V. Complete the following sentences. Choose your answers from the box.

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There are more words than you will need. 1. A tunnel is an underground … for a road or railway through a hill or under a river or the sea. 2. Any soil driven for a tunnel is called … 3. A lining is the … tunnel element. 4. Submarine tunnels can be … through the rock. 5. A portal connects the tunnel with the … 6. Tunnels can be classified according to the shape of the tunnel...

cross-section, rock, basic, ground surface, bored, passage VI. Look at the following diagram. What is the base of this classification? Can you complete it? Draw a similar diagram in your notebook and let your partner complete it.

VII. Complete the following sentences without looking back at the text. 1. There are several traffic tunnel types. They are … 2. Tunnels for water supply and sewerage, electric- and telecables are called … 3. A tunnel laid at 12m depth is called … 4. Submarine tunnels are erected by … 5. Tunnel construction methods are … VIII. Think of a tunnel and let your friend guess what tunnel it is. Model:

Traffic

?

? Mine

?

Tunnel

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IX. Look at the pictures below (fig. 12, 13). Try to describe tunnel shapes.

Horseshoe (flat bottom provides roadway)

Fig. 12

Circular (strongest shape)

Is it a pedestrian tunnel? Is it a tunnel for water supply?

Yes, it is. Yes, it is.

Is it a hydraulic tunnel?

Yes, it is. No, it isn’t.

Yes, it is.

Is it a tunnel for pedestrians?

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Fig. 13

X. Work in pairs. Speak about the longest railway and highway tunnels of the world using the table below. You may use the following phrases for help: As far as I know…; do you know what…; what is the longest…; what about…; as far as I remember…; what is its length…; somewhat about…; let me see…

Tunnel Location Year completed

Length kilometers

Seikan Channel Tunnel Daishimizu Simplon II Simplon I Shin-Kanmon Apennine Saint Gotthard Rokko Henderson Haruna Furka Saint Gotthard Nakayama

Japan United Kingdom-France Japan Italy-Switzerland Italy-Switzerland Japan Italy Switzerland Japan United States Japan Switzerland Switzerland Japan

1988 1994 1982 1922 1906 1975 1934 1980 1971 1975 1982 1981 1882 1982

53.9 50.0 22.2 19.8 19.8 18.7 18.5 16.3 16.3 15.8 15.4 15.3 15.0 14.9

Text 33

I. Listen and repeat: daylight cutting technique tunnel support face adit

['deIlaIt] ['kAtIN tek'ni:k] ['tAnl sq'pO:t]

дневная поверхность горный способ проходки тоннелей крепь забой штольня

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shoefly calotte vault central block side block lining blasting charge skip

[feIs] ['xdIt] ['Su:flaI] [kq'lOt] [vO:lt] ['sentrql 'blOk] ['saId 'blOk] ['laInIN] ['bla:stIN] [Ca:G] [skIp]

ходок калотта свод средняя штросса боковая штросса облицовка, обделка взрывные работы заряд взрывчатого вещества ковш

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own. II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. An-swer the questions of your partner. III. Read the following text and say what influences the choice of tunneling technique.

ROCK TUNNELING A tunnel is an underground way, which passes into a daylight at both ends.

To cope with different geological conditions the miners adopt various driving techniques. Cutting is the most ancient technique of tunneling.

The three principal features determine the cutting tunneling technique: 1. The tunnel cross section is divided into several areas which are developed

in turns. 2. The lining may be built in the developed sections while the ground may

be excavated from the rest of the tunnel face. 3. The temporary tunnel support of timber is used during the tunneling. The process of the cross section development for hard rock tunneling is as

follows. Initially the bottom adit is worked and the temporary tunnel support is built there. Then the vertical and inclined shoeflies are made from the bottom adit. They prepare the top adit or the top drift development.

The next operation to perform is to open the calotte i.e. the development of the top tunnel section. This tunneling stage requires, lining in the tunnel vault. Then the miners excavate the ground from the middle section (central block) and at last in the side sections of the tunnel (side blocks). The ground having been developed, the builders finish the lining erection.

Almost every tunnel job will involve short stretches of bad ground requiring

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a special technique of driving. The most important problem to solve is to choose the proper method for the ground development depending upon the changeable geological conditions. Rock tunneling involves various techniques of rock de-velopment for different ground types.

Hard-rock tunneling needs explosives, i.e. the rock must be broken by blast-ing. It requires blasting, loading the broken rock transporting it from the face, drilling and supporting the rock and ventilation after blasting. Safety is always the first consideration in tunneling and ventilation takes away the blasting fumes.

Hard-rock tunneling requires «drill-and-blast» technology. It represents the following stages: 1) to drill a blast-hole in rock with the aid of miner’s picks or blast-hole drills; 2) to place a charge in blast holes; 3) to set off a charge in blast holes; 4) to remove the toxic blast fumes from the face by ventilation; 5) to pro-vide the face inspection for revealing the charges that possibly did not blast.

Soft rock tunneling needs miner’s picks, blast-hole drills and loading ma-chines which are most efficient for sand, sandy loam and other types of incoher-ent ground. The broken rock is loaded into skips driven by electric locomotives, which run along the narrow-gauge track. The gauge in tunnels ranges from 6000 mm to 750 mm or 900 mm. Sometimes the broken rock is moved away by a conveyer belt. IV. Find 8 pairs of antonyms: V. Read about cutting technique once again and label fig. 14.

1 – _________________________ 2 – _________________________ 3 – _________________________ 4 – _________________________

5– _________________________ 6 – _________________________ 7 – _________________________ 8 – _________________________

ancient; permanent; fill; modern; vertical; bottom; previous; horizontal; temporary; begin; top; steady; excavate; following; finish; changeable

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Fig. 14

VI. Work in pairs. Answer the question of your partner. Use the phrases below to make up questions. Model: - Are they revising the project?

- No, they aren’t. They have already approved it. To choose the proper method; to excavate the ground; finish the lining erection; to discuss geological conditions; to blast the rock; to examine the ventilation; to transport the broken rock. VII. Complete the sentences. 1. Cutting technique of tunneling is the most … one. 2. During the tunneling according to cutting technique the … is used. 3. First the bottom … is worked. 4. The next stage is opening the … 5. The final stage is erecting the … 6. Hard-rock requires needs … 7. … is always the first consideration in tunneling. VIII. Complete the table without looking back at the text.

steps action

7

3

4

5

2 1

6

8

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1 preparing the bottom adit 2 … the temporary support 3 … the vertical and inclined shoeflies 4 … the top adit 5 … the calotte 6 … in the tunnel vault 7 … the ground from the central block 8 … the ground from the side sections 9 … the lining erection

Home Exercises I. Memorize the words from Ex. I page 127. II. Give a short summary of the text. Express your attitude to the problem of rock tunneling.

Text 34

I. Listen and repeat: riddle shoving jack ring girder bit hood breast board bulkhead distortion cutting edge muck

['rIdl] ['SAvIN 'Gxk] ['rIN 'gq:dq] [bIt] [hud] ['brest 'bO:d] ['bAlkhed] [dIs'tO:Sn] ['kAtIN 'eG] [mAk]

просеивать домкрат опорное кольцо буровое долото; сверло выдвижной козырек доска траншейного крепления перегородка деформация ножевое кольцо отвал, извлеченный грунт

II. Scan the text for about 10 minutes. For questions 1 – 4, choose the an-swer (A, B, C, D) you think fits best according to the text. 1. The tunnel boring machines are used to... A riddle the ground with pockets of methane gas. B increase water pressure. C minimize the risk of the rock inrush.

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D understand engineering. 2. A shield is a steel… A circle. B box. C oval. D cylinder. 3. Usually the shield length is … A about 30 m B above 50 m. C under 30 m. D about 50 m. 4. Most shields must be assembled… A in the shop. B on the job. C in the tunnel. D in the rock. III. Read the text and check your answers.

SHIELD-DRIVEN TUNNELS

Cutting as well as fire-setting techniques have been replaced by a higher level of technological and engineering understanding because the ground can be riddled with pockets of methane gas and stretches of high pressure water. All this poses great risk to the works. The tunnel boring machines (TBMs) are used to minimize or even to escape the risk of the rock inrush, great labor require-ments for the temporary support construction and ground excavation by separate sections. Technological advances resulted in shield driving. Mark Brunnel, a celebrated engineer created the idea of employing a shield to lead the tunnel ex-cavation.

A shield is a steel cylinder equipped with rotating cutter blades that supports a tunnel as it excavates. Its creation has made possible underwater tunneling through soft ground, sand, sand loam, silt, etc. Shield tunneling allows to de-velop the full cross section of the tunnel without dividing it into separate areas. In this case the driving speed may be 15 – 30 m per day.

The modern TBMs may be described as high-tech cylindrical factories, complete with laser-directed guidance and the now obligatory canteen and sleep-ing quarters. The machine diameter ranges from one to ten meters and depends on the tunnel purpose. The shield length reaches 30 or even 50 m.

The basic problems of shield tunneling are to overcome the ground frontal

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resistance and ground friction on the cylinder skin when shields advance. The so-called shoving jacks are mounted along the shield perimeter to solve these problems. The shoving jacks are rested by their ends against the tunnel lining and shield ring girders.

Rotating cutter blades or roller bits are called cutting edge. It cuts through the rock. The cutting edge may have a forward extension of its top section. This extension is called a hood.

Under its protection the miners can set the breast board far enough ahead the shield face to permit a full length shove.

Working pockets and bulkheads are also essential shield parts. Horizontal and vertical frames divide the front part of the large shield into pockets. These frames stiffen the shield structure against distortion from the loads on the cutting edge and provide platforms for the workmen to stand on when attacking the face and making the primary lining.

The bulkhead type of shield is used for certain kinds of ground. A port is built into the bulkhead of each working pocket to admit silt or soft clay to the tunnel through the shield.

Proper operation of the shield requires great skill and experience. Shield tunneling represents the advantageous excavation of underground space from many points of view. But it has some disadvantages as well.

First, there are non-mechanical shields and the miners have to use hand tools for the ground excavation, loading the muck and the lining erection.

Second, each type of the ground requires different shields and different technique in handling the shield. The ground may vary from section to section so the system of driving must be flexible enough to meet all the anticipated ground conditions.

Thirdly, shields can be assembled in the shop and shipped to the job site in one piece in case they are small. However, most shields must be assembled on the job, at the portal or at the bottom of the shaft because of their size. These op-erations are very expensive and call for considerable labor input. Besides, shield start up and dismounting involves heavy outlays. That is why it is not expedient to employ TBMs in all sorts of tunneling. IV. Match the English and the Russian equivalents.

escape equip blade driving overcome extension tool flexible

проходка инструмент гибкий преодолеть оборудовать нож избежать удлинение

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V. What notion is described? - to make a hole or a channel by digging the ground; - the flat cutting part of a knife; - the part of a tool that cuts or grips when twisted; - pulling or twisting something out of its usual shape; - a dividing wall or barrier VI. Work in pairs. Put 5 special questions to the text and answer the ques-tions of your partner. VII. Copy and fill in the table using the information above and your own knowledge.

Shield-Driving Tunneling advantages disadvantages

- allows to develop the full cross sec-tion of the tunnel without dividing it into separate areas; - …

- ground conditions are different; - …

Home Exercises I. Memorize the words from Ex. I page 130. II. Compare cutting technique and shield-driven tunneling.

Text 35

I. Read the text and find the main idea.

AUTOMOBILE TUNNEL UNDER THE ALPS Europe’s first automobile tunnel under the Alps, the 3.4-mile Great St.

Bernard Tunnel between Italy and Switzerland, was officially opened to traffic on the 19th of March 1969. The tunnel was under construction slightly over five years and costs about 38 million dollars. Actual digging started from both sides was under way from February 1959 to April 1961. Some 1.650 tons of explosives were used to excavate more than a million cubic yards of rock. The project also required 44.000 tons of steel for use in the construction of walls and roadbed, and 165.000 tons of reinforced concrete for lining the inside of the tunnel. The tunnel has a two-line roadbed, 24 ft wide and is 14 ft 9 in high.

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Leading up to it on both sides are several miles of approaches built on concrete stilts and roofed with concrete to protect the roads from snoe and avalanches and make them useable throughout the year. Up to now the Great St. Bernard Pass has been closed much of the year by snow.

More than 30.000 cars a year are expected to use the tunnel. Tolls range from 2.10 dollars to 4.65 depending on the engine, size of the car and the number of passengers. There are 12 other important tunnels under the Alps in central Europe all for rail traffic. Soon the second Alpine motor tunnel will be ready. It will connect Italy and France under Mont Blanc. II. Read the text word by word and complete the following words. Tr · · · ic ; ro · ·; · in · · ·; r · · d · e ·; con · · · · e; · · ll; · · nn· · ·; p· o· e· t; t· · · · l. III. Give Russian equivalents to the following word combinations: to be under construction; to be under way; to be used to excavate; to make something useable; throughout a year. IV. Give one word instead of the underlined word combinations. gradeate, extend, mechanize, accumulate, evacuate, contract, weaken, prolong, anchor 1. Regular maintenance will give the tunnel a longer life. 2. The ends of the cables are fixed firmly and safely in foundations. 3. The bar of metal will get shorter while cooling. 4. It is first necessary to take the air out of the tube by means of an air-pump. 5. The motorway will gradually be made longer. 6. This work was formely done manually, but now it is carried out by machines. 7. More and more carbon collects in the tunnel. 8. The tube is marked off at intervals as the distance from the transmitter increases. V. Read the text and say if these statements are true, false or not given. 1. The first automobile tunnel under the Alps in Europe connect Italy and France. 2. The Great St. Bernard Tunnel is 3.8 miles long. 3. Digging between Italy and Switzerland was made manually. 4. Lining of the tunnel under Alps is made of reinforced concrete. 5. Tolls are constantly rising. 6. The second Alpine motor tunnel is built under Mont Blanc. VI. Answer the questions to the text. 1. When was Europe’s first automobile tunnel under the Alps opened? 2. What was the inside of the tunnel lined with? 3. How many cars a year are expected to use this tunnel?

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4. What will protect the roads from snow and avalanches? VII. Make up a circle. Try to tell a collective story about the first automobile tunnel under the Alps (every student must say a sentence).

Text 36

I. Listen and repeat: pilot heading divergence combustion duct exhaust solution

['paIlqt 'he-dIN] [daI'vq:Gqns] [kqm'bAsCqn] [dAkt] [Ig'zO:st] [sq'lu:Sn]

направляющая штольня расхождение, отклонение сгорание канал, трубопровод вытяжное устройство; выхлоп решение

II. What do you know about the Mursey Tunnel? Where is it situated? When was it built? What is its length? III. Read the text and check your answers.

THE MERSEY TUNNEL The cities of Liverpool and Birkenhead are joined by a tunnel which goes

under the river Mersey. It is the famous Mersey Tunnel, one of the biggest underwater tunnels in the world. Its total length is over two and a half miles. During the year 1956 more than 10 million vehicles used the tunnel.

Its construction has been a great engineering achievement. The work started in December 1925 on the Liverpool side and a few months later on the Birkenhead side. It had been decided to approach the work by driving from each bank of the river two pilot headings, an upper and a lower one, which would meet under the middle part of the river.

Vertical shafts were sunk on both sides of the river and the excavation work began. At first the working face on the heading was broken up by compressed air drills, later explosives were used. The headings met on the 3rd of April, 1928, twenty-seven months after the work had began. The divergences in line and level were found to be about an inch, showing how accuratly and correctly the survey work and the determination of working levels had been done.

The next stage of the work was the enlarging of the pilot headings into the full-sized tunnel. Steel, cast iron and concrete were used in lining the tunnel.

From the very start it was realized that the ventilation of a tunnel of such a length, which was to be used by vehicles propelled by internal combustion, would be a very difficult problem. Finally, a system of ventilation was adopted

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in which air is blown into the tunnel through ducts at roadway level and drawn off along the roof through exhausts.

The Mersey Tunnel was completed in 1934. It was opened on the 18th of July 1934. At the time it seemed a complete solution of the communication difficulties that had existed between Liverpool and Birkenhead. Today it is obvious that the solution has been only temporary. The ever-increasing exports from the part of Liverpool and the rapid development of Merseyside as an industrial centre have resulted in a great increase in motor traffic through the tunnel. IV. Replace the words in bold with others from the list.

explosives, construction, owing, affected, increase, tunnellers, conducted The Mersey Tunnel in England belongs to the world’s longest underwater

tunnels. Its building was carried out from the opposite sides of the river and the workers were to meet in the middle of the river beneath its bottom.

At first compressed-air drills were used for boring the tunnel, and the rate of construction was not very high. Later, however, tunneling was speeded up due to the application of charges.

When completed, the Mersey Tunnel became an important means of com-munication between the two towns because it permitted to considerably raise the flow of road traffic. In addition, the traffic was not influenced by weather conditions.

V. Correct the statements. The first example is made for you. 1. The Mersey Tunnel links Liverpool and Birmingham. – Oh, no! You are wrong. The Mersey Tunnel connects Liverpool and Birkenhead. 2. The total length of this tunnel is over two and a half kilometres. 3. The work started on the Birkenhead side. 4. A system of ventilation left much to be desired. 5. Construction of the Mersey Tunnel lasted 6 years. VI. Complete the diagram showing the construction of the Mersey Tunnel.

vertical shafts ______

boring by drills application of ___________

enlarging of _____________ lining the tunnel

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VIII. Render the information about the Mersey Tunnel (one by one) using the following word-combinations: The need is stresses to employ (подчеркивается необходимость использования)…; … is examined (исследуется)…; … is investigated (исследуется)…; … is analysed (анализируется)…; … is formulated (формулируется)…; attention is drawn to (обращается внимание на)…; data are given about (приведены данные о)…; attempts are made to analyse (делаются попытки проанализировать)… .

Home Exercises I. Memorize the words from Ex. I page 135. II. Open the brackets. 1. The tunnel near my house … this year (to build). 2. Most of the rivers … already … with canals (to connect). 3. The new methods of bridgework … good results (to bring). It is evident now. 4. France and Spain … from each other during the winter snows (to isolate). 5. What calculations … you … yourself and what … by your tutor (to do)?

Text 37

I. The following information may be interesting for you. Read it and ex-press the main idea.

TUNNELING COUCH OF THAMES The National Research Development Corporation has backed an experiment

contract awarded to Edmunds Nuttall, Sons and Co by the London Transport Executive. The 250000 contract is for the design and manufacture of a tunneling machine which will be based on a process patented six years ago by consulting engineers Mott, Hay an Anderson. This process involves the use of bentonite, under pressure, both to support the face and to remove spoil from the chamber.

It is hoped that if the experiment is successful the machine will be able to drive tunnel through the wet gravels in London, south of the Thames. This will enable the Underground System to be extended into the area which previously has not been feasible. The new Fleet Line, which has not yet been started, could partly cover the area.

The contract is expected to last about two years. The machine should be built within nine months by Nuttall’s subsidiary, Robert L. Priestley. It will be tested on a 600 ft length of tunnel, cast iron lined, which will be driven at New

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Cross, South London. Extensive tests and measurements will be made to check the progress of the experiment and determine the value of bentonite in tunneling.

Medical advisers to tunneling professions are also interested in this applica-tion as if successful it could start a trend away from the use of compressed air and its associated risk particularly bone necrosis. II. Make up questions from the words and answer them. 1. Contract / what / experiment / Research / was / by / the / National / Develop-ment / Corporation / backed? 2. What / will / tested / machine / be? 3. What / involved / in / be / test / will? 4. How / will / the / valid / contract / be / long? 5. Why / in / interested / are / medical / application / advisers / of / the? III. Imagine that you were a participant of the experiment described. Write a report saying about the results.

Home Exercises I. Complete the word-building table.

Verb Noun use extend ………………….. determine ………………….. associate

………………….. ………………….. measurement ………………….. application …………………..

II. Do the puzzle and you will find out what words are written on the wall of one of London Underground stations.

T S I H L E N U T N H C I W HS R N U N D R U E H T E S E M A T H F M O R T S I HT I O N S T A S A W H T E F S T I R L E N U T N R E V ED R E N I V B E E N A H TH T E R R V I E . . .

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Text 38

I. Listen and repeat: jam means complement rolling stock tap off incorporate collision bottleneck exceed

[Gxm] [mi:nz] ['kOmplImqnt] ['rqulINstOk] ['txp"Of] [In'kO:pqreIt] [kq'li:Zn] ['bOtlnek] [Ik'si:d]

затор, «пробка» средство, способ дополнение подвижной состав отвод, ответвление включать (в состав); объединять(ся) столкновение; конфликт сужение; «пробка» превышать, превосходить

II. Which of these words do you associate with underground?

train rails tarffic difficult congestion convenient non-street quick unreliable cheap station pollutant stream

III. Is it convenient to travel by underground? Why do you think so? Read the text and add some ideas to your answer.

GENERAL IDEA OF THE UNDERGROUND

In metropolitan areas and in regional urban areas it is difficult to ensure the basic function of roads – i.e. safe and smoothly flowing traffic – because of traf-fic congestion and frequent daily traffic accidents. Users want safer, more con-venient and higher-quality traffic services that meet their needs better. It is evi-dent that underground being an urban non-street railway system can solve the problems of carrying passengers, as well as the problems of traffic jams, air con-tamination and noise. The underground railway is the quickest, safest, most reli-able and comfortable means of travel which can be found in 80 cities all over the world. Twenty-eight countries can afford these metropolitan traffic facilities not only in their capitals.

But from the technical point of view the underground railway system is very expensive and complicated constructional works providing much higher traffic efficiency than ordinary roads. In addition local train services and high-speed tram links which look like the underground railway system complement the highly developed public transport network. The underground railway system dif-fers from the high-speed tram in the track, the overall dimensions of the rolling stock and the method of tapping off the current.

The underground railway system incorporates subsurface lines, ground based lines and elevated lines located on trestle bridges.

The underground railway carrying capacity depends on the number of

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coaches which ranges from two to eight per train, the seating capacity which ranges from 90 to 270 passengers per coach and the frequency of train running. The time intervals range from 90 seconds to six minutes.

The underground railway systems all over the world use two types of line intersections. Some foreign subways use one-level lines. The passengers can get to their destination or other stations using one line without changing trains. The underground railway lines in Russia are laid in different levels. This type of lines offers absolutely safe service from any possibility of the train collision. To allow passengers to change from one train to another, underpasses are provided at various underground stations.

The expected growth in the use of all possible means of public transport will cause chronic traffic congestion at the bottlenecks and noise will exceed the re-quested limit. In considering these concerns the underground railway has no al-ternative. In addition to its other beneficial effects it provides the environment quality standard. IV. What notions are defined below? - railway engine with several carriages or trucks linked to or pulled by it; - a crowded mass of vehicles that makes movement difficult or impossible; - the solid surface of the earth; - an instant of one object striking against another violently; - a place where trains stop on a railway line V. Read the text and correct the following sentences: 1. The London Metro is the longest one. 2. The length of the Budapest Metro comes third after London and New York. 3. The first underground railway lines were laid in 1868. 4. Paris has the shortest metro in the world. 5. The Metro in Moscow was being built during four long years.

The earliest underground railway lines were erected in London in 1863. The idea was proposed by Charles Pearson in 1843. According to his project almost all lines were to be laid close to the ground surface. The London Metro has come to be called the Tube. Its length is about 400 kilometers but it is not the longest one.

New York was the second city to build the subway. The first track was laid in 1868 and nowadays its length ranks next to nothing. The USA subway cur-rently heads the list of the underground railway systems because eleven cities in US involve subway into public traffic and its overall length is 1060 km.

Budapest built its underground in 1896 and occupies the third place in the history of the metro construction.

The length of the Paris underground is about 200 km and it comes third after

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London and New York. The shortest metro line was built in Turkey. Its length is only 600 m but Is-

tanbul is very proud of the metropolitan means of traffic. In June 1931 it was decided to start the building of the Metro in Moscow. It

was put into operation on May 15, 1935. It was called the record period of time by the world press. The Metro was erected in accordance with the Moscow Mas-ter Development Plan but since then building work has not stopped for a single day. The surface buildings and underground halls of the Metro stations are spa-cious, well lit and ventilation facilities are essential. They are equipped with fans, dust collectors and mufflers. The metro stations are decorated with marble, bronze, aluminum and glass. The cleanliness of the Moscow Metro has been commented on by all users. “No smoking” became a hard and fast rule on the very first day of its existence. All the deep stations have escalators. The train speed is 70 – 90 k/ph.

New metro lines are being constructed all over the Russian Federation and six Russian cities have already afforded the underground. VI. Find one meaningless word and change it. Give the main idea of the text.

The underground design in Rome was proposed in 1881 but the erection of the Metropolitan began only after the World War II in 1946 and its ten stations were put into operation in 1955. The builders found ancient ruins and antique statues while digging the puttles. Many of these statues and mosaics were well preserved and at present they decorate the concourses of the Termini – main railway station in Rome. All these marble gods and goddesses remember the an-cient Roman carriages and nowadays watch hi-tech means of transport.

The spacious halls of the underground stations were most reliable refuges for people in many cities during the World War II. Besides, many ancient books and rare collections from the museums spent the war in the underground puttles. The underground railways were prepared for any emergency situations. In Lon-don some of the unused Tube puttles five miles in length were occupied by an airplane producing plant. VII. Look through the information above (Ex. III, V, and VI) and complete the following sentences. 1. Underground can solve the problems of… 2. The underground railway is the … means of travel. 3. The underground railway system differs from the high-speed tram in… 4. The earliest underground railway lines were constructed… 5. The overall length of the American underground railway systems is… 6. The Metro in Moscow can be described as… 7. The Roman underground is decorated with…

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Home Exercises I. Memorize the words from Ex. I page 139. II. Write an article comparing automobile roads and underground.

Text 39

I. Listen and repeat: sleeper chute bracket pantograph lobby running tunnel crossover dead-end concourse pull chamber stairways tunnel power driven station

['sli:pq] [Su:t] ['brxkIt] ['pxntqugra:f] ['lObI] ['rAnIN'tAnl] ['krOsquvq] ['ded"end] ['kONkO:s] ['pu:l'CeImbq] ['steqweIz 'tAnl] ['pauqdrIvn 'steISn]

шпала водоотводный лоток кронштейн токосъемник поезда коридор, холл перегонный тоннель съезд тупик зал ожидания натяжная камера эскалаторный тоннель приводная станция

II. Scan the text for about 10 minutes. For questions 1 – 4, choose the an-swer (A, B, C, D) you think fits best according to the text. 1. The underground railway tracks are laid on… A) crushed rock. B) gravel. C) concrete base. D) sand. 2. The sleepers of the railroad track are … long. A) about three meters B) about two meters C) about a meter and a half D) about one meter 3. The lining in main line tunnels is made of the … parts. A) reinforced concrete B) cement concrete C) concrete

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D) cement 4. Passengers can change levels using… A) lobbies. B) power-driven stations. C) moving stairways. D) pull chambers. III. Read the text and check your answers.

THE UNDERGROUND RAILWAY SYSTEM STRUCTURES

The track construction of the Underground Railway System differs from the usual railway track. The sleepers of the railroad track rest upon a bed of crushed rock or gravel, which is called ballast. The tracks of the underground railway are laid directly on concrete base. The main idea of using concrete in this case is to keep air free from dust but it involves heavy outlays. Were the track imbedded in foundation materials i.e. slag, gravel, ash, sand, hard earth or even broken stone, the trains would be followed by the dust clouds.

The ties or sleepers in the metro are shorter than those of the railroad track, which are 2,7m long. The metro sleepers are only 0,9 m long. They are sepa-rated by a chute. The contact rail is laid along the whole track and arranged to carry high voltage current of 825 volts. It is attached to the brackets and trans-mits the direct current to the train electromotor through the pantograph.

The underground railway subsurface and oversurface structures involve sta-tions, main line tunnels, lobbies, tunnels for moving stairways and escalators, underpasses, ventilation and sanitary engineering as well as a power supply sys-tem.

The main unit of any underground railway system is a main line or running tunnel. All running tunnels may be subdivided into single-lane one-way tunnels, double-lane and four-lane tunnels. The New York Underground has two usual lanes and two high-speed lanes called «expressway». The lining in main line tunnels is of circular shape. As a rule, it is erected of the reinforced concrete segments or cast iron liners, i.e. it is assembled from separate units. Crossover tracks can divert the trains from one track to another. The trains may be in-spected and repaired at the dead-ends.

Needless to say the stations represent one of the main parts of the under-ground railway system to provide the wide choice of services for passengers. At-tractively designed underground structures represent a continuation of the above-ground architecture. The stream of passengers can move freely through entrances and exits of the aboveground and underground lobbies using special staircases linking the underground areas with the over surface streets. After a while, passengers no longer notice whether they are moving above or below

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ground because the structural layout itself as well as the different functions of-fered within the space, extend the main «room of action» and also create the at-mosphere of «city within the city». Underground stations are regarded as most efficient because they provide the spacious lobbies and leave the city areas for other public needs. One underground station may have up to nine entrances and exits. The height difference inside the underground lobbies is almost completely canceled out by the structural arrangements. The width of some underground passages ranges between two and six meters, their height cannot be less than 2,5 m. The passengers can move from one station concourse to another or from one entrance – exit lobby to another one walking along these underpasses. In addi-tion, escalators and stairways are provided to allow passengers to change levels.

An escalation complex involves an inclined stairways tunnel for the three stairways within it, a power-driven station to move the staircases and a pull chamber. As a rule, this tunnel’s diameter is 8,1m. The escalators of Russian production provide the lifting of the passengers up to 65 m. IV. Match the English and the Russian equivalents. Use the English words in the sentences of your own.

rest base ash subdivide entrance create lifting

вход создавать опираться подъем зола основание подразделяться

V. Mark these sentences true, false or not given. 1. _______ There is no difference between the usual railway and underground railway tracks. 2. _______ When the underground railway tracks are imbedded in ash, the trains are followed by the dust clouds. 3. _______ The sleepers of the railroad track are separated by a chute. 4. _______ The dimensions of the metro station are influenced by the number of passengers to be carried. 5. _______ Any underground railway system can easily work without a running tunnel. 6. _______ An escalation complex consists of a stairways tunnel, a power-driven station and a pull chamber. VI. Restore the text (guess the words under the blots) and retell it to your partner.

The underground stations may be of different structural layout. There are

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offboarding platforms and boarding platforms. Platforms are very important parts of the station concourses because they

accommodate passengers and allow them enter, leave and change the trains. To determine the optimum capacity of an underground station it is necessary to consider the busy rate i.e. number of passengers carried through this station.

The main quantity index of any station is rated within the following limits: - the quantity of passengers for an ordinary station must be equal to 20 – 30 % of a total train capacity; - the quantity of passengers for the stations located near terminals, theaters etc. must be equal to 50 /n of a total train capacity; - the quantity index for the stations next to large stadiums is equal to 100 % of an overall train capacity.

The dimensions of the station are influenced by the number of passengers to be carried.

The structural layout calls for due attention to the station length and height, the platform width and the length and height of the underground passages. The width of an off-boarding platform must be 10 and in the case of a board-ing platform – not less than 4 m each. Some platforms incorporate sliding doors, which open only when trains are ready to receive passengers. Moreover, the structural layout depends on the erection technique. As a rule, the floors of the shallow stations are made of flat panels. The structure of such stations involves columns, cross-bars and floor slabs as well as walling blocks.

Three vaults structures are employed for the deep stations. The central vault is used for platform and the side vaults are used for lanes. The vaulted stations can be erected with columns which serve as the principle bearing element or with the pylon frame.

Home Exercises I. Memorize the words from Ex. I page 142. II. Make a report on the difference between the usual railway and under-ground railway tracks.

Text 40

I. Listen and repeat: upkeep supervisor

['Apki:p] ['su:pqvaIzq] [gxN]

содержание; ремонт диспетчер, контролер, инспек-тор

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gang shift derail gauge fastening shipping clearance rod crust incipient screed gutter encasement contamination foul fan muffler dilute leakage

[Sift] ["dI'reIl] [geIG] ['fa:snIN] ['SIpIN'klIqrns] [rOd] [krAst] [In'sIpIqnt] [skri:d] ['gAtq] [In'keIsmqnt] [kqn"txmI'neISn] [faul] [fxn] ['mAflq] [daI'lu:t] ['li:kIG]

бригада рабочая смена; сдвиг, смеще-ние сходить с рельсов колея; калибр крепление, крепежная деталь транспортные габариты стержень; рейка; пруток кора, корка начальный, зарождающийся правило; штукатурный маяк ливнесток, дренажная канава, желоб устройство защитной оболоч-ки; облицовка, оболочка загрязнение; заражение грязный вентилятор звукопоглощающее устройст-во разжижать, разбавлять; разре-жать утечка

II. Scan the text and put the items in the correct order. Tunnel lightning. Tunnel maintenance. Railway track maintenance. Tunnel lining. Shipping clearances testing. Ventilation facilities. Water discharging. III. Read the text and check Ex. II.

TUNNEL MAINTENANCE

The current tunnel maintenance and care is much more expensive as against the bridge and culvert upkeep. A tunnel supervisor is in charge of a current su-pervision. He works side by side with a gang shift belonging to a maintenance section of the railway.

Needless to say there are no negligible problems in tunnel maintenance be-cause a reliable tunnel operation during the service life depends on many fac-

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tors. Special attention in the tunnel is given to the maintenance of the railway

track which is examined daily. To maintain the railway track in proper condition means avoiding disastrous effects which may occur if a train derails. The tunnel supervisors’ attention is attracted by the gauge (1520 mm), the condition of the rail fastenings and joints. In addition two parallel rails must be supported at the same level.

The next problem to observe is a tunnel width and clear height to provide safe passage for trains. These shipping clearances are tested by a special measur-ing rod and a band or a special trolley equipped with a frame matching up the tunnel height and width.

The third problem is caused by the tunnel lining in case it is erected in the seismically active areas. The lining is influenced by the Earth’s crust shift and other displacement processes occurring within a massif. Tunneling through vari-ous sorts of rock can result in different effects and conditions influencing the lining especially when the blasting technique, is employed. Permanent supervi-sion and inspection is set up for the lining elements in case of shifts in block joints or incipient cracks in concrete and iron cast segments. The tunnel supervi-sors use special screeds attached to the lining surface to watch the dynamics of the running processes.

Water discharging is considered to be another complicated problem turning to become most important one for the tunnels, which are driven under the severe climatic conditions. For instance, the railway tunnels along Abakan-Taishet mainline in Siberia can suffer from the ice crust in gutters in winter when the water freezes and binders or even blocks train running.

The gutters are built at both sides of the railway track for water discharging. The water entering the tunnel is calculated and rated value influences the dimen-sions of the gutters and their lengthwise grade. The gutters appear to be a vital element in tunnel operation and call for extra maintenance cost under low tem-peratures because they need heating or special encasement for warmth-keeping.

There are some more problems facing the tunnels and above all ventilation and lightning should be taken into consideration.

Ventilation is among the most complicated problems which vehicular tun-nels face under operation. Ventilation facilities are essential because the under-ground road is a motor way within a tunnel structure. Air contamination calls for various types of ventilation facilities due to toxic auto emissions. Tunnel design takes full account of all the possibilities to provide a sound layout of the tunnel itself and efficient arrangement of ventilation facilities.

The simplest ventilation technique offers to arrange both ports at different levels providing natural ventilation due to the difference between air pressure at both ends.

One more idea of tunnel design may be applied to the large-diameter short

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tunnels which can be oriented along the dominating direction of the winds pro-viding adequate natural ventilation.

But the majority of the tunnels need artificial mechanical or forced ventila-tion and face the problem of estimation the volume of the air required. There is a special estimation technique taking into consideration the tunnel dimensions, the volume of traffic, etc. The general tunnel ventilation involves blowing, exhaust and combined ventilation. The blowing ventilation supplies fresh air from the unpolluted source – usually at the portal. The air is forced through a pipe and discharged at a place where it is needed. The foul air drifts back to the portal. By the exhaust method, foul air is pulled out through the pipe and the fresh air en-ters at the portal. The combination of these methods uses the fans to draw out the dust and auto emissions and then the fan are reversed.

Many tunnels are designed with ventilation stations including the ventilation tower and machinery rooms equipped with fans, power receiving and transform-ing equipment, dust collectors, mufflers and ventilation control devices. Some tunnels are equipped with a lateral flow ventilation system. In this system the air taken in at the ventilation station is fed into the tunnel to dilute auto emissions. The air is discharged from the tunnel after the dust has been removed from it. The name of the system derives from the fact that the air for ventilation flows laterally in the motor way through the feeding and discharging ducts.

In a concentrated discharge system, diluted auto emissions are absorbed by force near the entrance of a tunnel and discharged after the dust is removed from them. This system controls the leakage of exhaust gas from the tunnel entrance.

Tunnel lightning is very important from the point of view of safety meas-ures. If an accident occurs in a tunnel road in a city, it will have a major effect not only inside the tunnel, but also on urban activities on the surface because vehicles may carry hazardous loads. That is why special consideration is given to lightning at the design development phase. For instance, some tunnels in Switzerland are equipped with solar batteries which are used in remote areas in the mountains. IV. Find 11 pairs of synonyms: V. What notion is explained by the following definition?

disastrous; poisonous; various; catastrophic; safe; necessary; escape; protected; happen; different;

proportions; toxic; town; remove; essential; phase; dimensions; exhaust; occur; leak; urban; stage

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- equipment for providing light for a room, building, etc; - to allow air to enter and move freely through a room, building, etc; - a device with blades that are operated mechanically to create a current of cool air; - to allow liquid or gas to get in or out wrongly; - a device that fix something firmly; - a thing that is difficult to deal with or understand VI. Use the following phrases in the sentences of your own and let your partner translate them. In charge of; needless to say; side by side; depend on; in addition; result in; due to; taking into consideration; from the point of view of. VII. Complete the following sentences. Choose your answers from the box. There are more words than you will need. 1. Tunnel maintenance includes railway track maintenance, shipping clearances testing, water discharging, ventilation, lightning and … inspection. 2. The dynamics of the running processes in the seismically active areas are tested by… 3. … call for extra maintenance cost under low temperatures. 4. The majority of the tunnels need … ventilation. 5. … must be taken into consideration at the design development phase.

lining lightning forced screens screeds gutters forcing VIII. Cross out the words/word combinations, which cannot be used in de-scription of tunnel maintenance. current, careful, difficult, expensive, negligible, necessary, labour-intensive, profitable, interesting IX. Retell the text using Ex. II and the word combinations below. 1. The title of the story I want to tell you is… 2. First of all… 3. Second I would like to say that… 4. As far as I understand… 5. In fact… 6. As far as I remem-ber… 7. In conclusion I’d like…

Home Exercises I. Memorize the words from Ex. I page 145. II. Change the Voice of the sentences where it is possible. 1. Tunnel supervisors gave special attention to the maintenance of the railway

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track. 2. They erected a tunnel in the seismically active area that’s why there are a lot of problems with it. 3. We are going to use the blasting technique. 4. The tunnel was closed because of the damaged ventilation. 5. They need much more money for gutters repairing.

Text 41

I. Listen and repeat: failures avalanche mayhem mitigation withstand building code precision gust bay accretion impending ablation scour constriction slimy brittleness

['feIljq] ['xvqla:nS] ['meIhem] ["mItIgeISn] [wID'stxnd] ['bIldIN 'kqud] [prI'sIZn] [gAst] [beI] [q'kri:Sn] [Im'pendIN] [xb'leISn] ['skauq] [kqn'strIkSn] ['slaImI] ['brItlnIs]

авария, повреждение; неудача снежный обвал, лавина нанесение увечья смягчение, уменьшение противостоять, выдержать строительные нормы и правила точность; четкость; аккуратность порыв ветра пролет моста прирост; увеличение предстоящий, неминуемый, грозящий снос; размывание пород; таяние ледни-ков промоина, размыв сужение, сжатие, стеснение вязкий; скользкий хрупкость

II. You are going to read a text about failures and collapses of the construc-tional works. Five sentences have been removed from the text. Choose from the sentences A – E the one that fits each gap (1 – 5) to complete the text.

FAILURES AND COLLAPSES OF CONSTRUCTIONAL WORKS The main reasons causing the failures and collapses of the constructional

works can be divided into three groups: 1) insuperable disasters (earthquakes, hurricanes, floods and avalanches); 2) imperfection of the engineering and technical calculations of the struc-

tures (knowledge insufficiency concerning true behavior of the structure and the forces acting on the structure);

3) negligence, ignorance and violation of the construction, operational and structural safety.

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Let’s consider some of the well-known cases of failures and collapses of the constructional works caused by different reasons. Of all the frightening things of the world none is so frightful as an earthquake. 1 More than 100,000 quakes occur each year around the globe. Sudden, abrupt and violent shifts of the Earth’s crust result in vertical up to 7m and horizontal up to 4m displace-ments. In response to such displacements the spans can be thrown off the sup-ports because the piers themselves can be damaged and to a great extent move into an inclined position or even displaced.

But it is worth noting that during the most reported quakes the construc-tional works have suffered not nearly so much as other civil-engineering works because of the mitigation of earthquake damage. The earthquake in Japan crushed 85 % of dwellings in Tokyo on September 1, 1923. But the bridge works could withstand the disaster and only 337 from a total number of 1028 bridges failed. 2 .

Hurricanes also cannot result in the bridge collapse because at present the building codes take into consideration the forces of the most violent winds and calculate them with great precision. In 1879 the bridge having five spans 75 m long was thrown off the piers on the lake Tay in Great Britain. The train moving along the bridge at the moment of a severe gust added an extra area for the im-pact of the wind the speed of which was about 140 kph. In 1904 the viaduct supports 90 m high were overthrown and the 76 m long bays fell down under the wind blowing at 280 kph in St. Paul City, U.S.

3 In 1938 the ice accretion or ice jam which was more than 27 m thick and 120 m long cut the abutment of the arch span 256 m long on the Niag-ara River, U.S. The bridge had been in service for forty years and the ice level twice reached the impending danger point during its service life. 4 .

The ablation and scour of the support foundations resulted in the bridge col-lapse on the Uvod-river in Russia in 1881. The speed of the river current in-creased because of the channel constriction and leads to the 5 m deep hollow in the soft slimy ground.

The lack of the knowledge about the metal behavior led to the bridge col-lapse in Belgium in 1938. 5 This metal condition is called brittle-ness or shortness of steel. It is caused by the high carbon content of steel. A Ice impact is also rather dangerous for the bridge works.

B No place on earth may be safe from the possibility of tectonic mayhem.

C

When the air temperature dropped abruptly to the low subzero points some of the metal elements of the arch span burst even without any addi-tional loads.

D And in fact the Great Tashkent Еarthquake in 1966 did not break down

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or could seriously distract any constructional work. E

The last ice jam was building up during 36 hours but nothing was done to blast it off.

III. Read the text once again and make words from the letters (all the words are in the text). aClolseps; tiasseDr; Syfeta; uQkae; vOrewhrto; neDagrsuo; stBru; nuricHare; onrgacneI; fuSref IV. Match the given words with their common and special meanings (con-sult the dictionary). In what meaning are these words used in the text? Common meaning Special meaning work globe break wind speed metal channel ground

1) скорость 2) работа 3) ветер 4) металл 5) разрушаться 6) канал 7) земной шар 8) земля, грунт

a) конструкция b) дутьё c) колокол воздушного насоса d) дроблёный камень e) жёлоб f) светочувствительность g) заземление h) осветлять

V. Do the puzzle. 1. a large quantity of water; 2. a mass of snow that slides rapidly down the side of a mountain; 3. a place of residence; 4. the solid surface of the earth; 5. land;

6. a hard layer; 7. a sudden fall; 8. a long bridge, usually with many arches, carrying a road or railway across a river, valley, etc; 9. a sudden strong rush of wind

d

a n g

e o u s

1

6

2

9

3

8 7

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VI. Read the text and say if these statements are true, false or not given. 1. In 1883 in Great Britain the 9 m span failed just at the moment when a train was moving with the speed 65 kph. 2. In 1879 in Great Britain the bridge having five spans 75 m long was thrown off the piers. 3. The Tacoma Bridge was destroyed due to the amplification of the vertical and hormonal vibrations created by the resonance in a mild gale. 4. In 1938 in Belgium the hurricane caused a bridge to collapse. 5. The Quebec Bridge in Canada fell into the water because of the technological violation. 6. A stream of water and mud gushed into the Northern-Muya Tunnel and stopped the work for several years. 7. In 1940 the main span of the suspention bridge across the Tacoma River in the USA collapsed.

Home Exercises I. Memorize the words from Ex. I page 150. II. Write down the summary of the text in 50 – 70 words and don’t forget to express your own opinion. The phrases below and the key words you have written will be helpful. I believe…; In my opinion…; The way I see it…; It seems to me that…; As far as I am concerned…; I completely disagree with the idea that…; I fully sup-port… .

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Beyond the ’94 Deauville Confer-ence...

Since engineers began to build bridges, they have looked for ways to increase span lengths. Bridge design can be seen as the pursuit of minimum of dead load to satisfy a span's re-quired stiffness. This effort becomes more interesting and more important as the span increases. Sound concep-tual design, proper detailing and sim-ple methods of construction will lead to good performance of bridges. Each combination of materials and structural systems imposes its own lim-its. To understand, indeed to feel how structures and (new) materials

behave and interact is the key to creat-ing new conceptual designs for high performance structures, whereas ever more refined methods of structural analysis probably will not lead to new solutions. The following proposal, a "spatial" suspension bridge for bar-rier-breaking spans, is a highly chal-lenging concept. Among the many pos-sibilities it raises, might it not also find application for other types of long-span structured? Prof. Eugen Brühwiler Chairman, IABSE Publications Com-mittee

BREAKING BARRIERS OF SCALE: A CONCEPT FOR EXTREMELY LONG SPAN BRIDGES Christian Menn, Prof. em. Chur, Switzerland

David P. Billington, Prof. Princeton Univ., Princeton, NJ, USA

Introduction

For each bridge project, span length is an especially important parameter. It is a visual impression of the structure's technical efficiency and it has a con-siderable influence on construction costs: For every structural system, both the quantities of construction materials and the design and erection problems grow disproportionately as the span

increases. Moreover, each structural system exhibits, by simple extrapola-tion, an economically limited span length whose location on a cost/span diagram can be established where the cost will increase exponentially. With fundamental changes in structural sys-tems, new construction techniques, new or more efficient construction ma-terials, the span limit can be increased. The challenge to exceed previous lim-its is probably the most important rea-son why long spans continually have fascinated bridge engineers.

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Fig. 15 Since the beginning of the Industrial Revolution - with its scientifically pro-portioned bridge designs - the longest spans have been achieved by suspen-sion bridges (Fig. 15). First were the chain bridges like the Menai Straits Bridge of 1826 with a span of 177 m. After that came the de-velopment of the in situ cable spinning technique with wires, whereby the erection problems were significantly reduced. With the great bridge over the Saane River in Fribourg, Switzerland, in 1834 a span of 274 m was reached, and in 1848 the ill-fated Ohio River Bridge at Wheeling, USA, was the first to reach the span of 1000 ft. (308 m). The longest leap in the 19th century was certainly the 487 m long span for the Brooklyn Bridge in 1883. With the construction of the George Washington Bridge in 1931 between New York and New Jersey, O. H. Ammann showed a new way to design suspension bridges.

He increased the record, span from the 564 m of the Ambassador Bridge in Detroit to the unbelievable 1067 m, whereby in View of the high dead weight or rather the "cable stiffness" (a consequence of the great dead weight), he greatly reduced the stiffening truss and even concluded that he could eliminate it entirely when only the up-per deck was in place between 1931 and 1962. At the end of the 20th Cen-tury the 2000 m span limit will be ap-proached by the Akashi Straits Bridge in Japan. Structural Systems for the Longest Spans Great spans are doubtless achieved only with cable-supported bridges. In principle the following cable-support-ed bridge systems are known (Fig. 16):

(a) Suspension bridge with cables anchored in the ground: up to now this is the system used for the longest spans.

(b) Suspension bridge with cables anchored against the deck girder: used only for small bridges and small spans, because the girder must first be con-structed on a scaffold.

(с) Cable-stayed bridge with cables anchored in the deck girder: almost all cable-stayed bridges are built with this system. The compressive force intro-duced into the girder by the cable stays and the cantilevered construction stage is critical limitations for the span length.

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Fig. 16 (d) Cable-stayed bridge with cables

anchored in the ground (with ex-pansion joints at either end of the girder): seldom used because the ca-bles must run the entire length between the ground anchorages.

Of the known cable-supported bridge systems, only the classical suspension bridge with cables anchored in the ground is suited for the longest spans. Depending upon the ratio of bridge width to bridge span, suspension bridges are - especially under wind loading - sensitive to vibrations; and for extremely long spans, in the region of 3000 m, this problem will be domi-nant. At the IABSE-FIP conference of 12-15 October 1994 in Deauville, Theme 4 was devoted to new developments in the construction of extremely long spans. The main problem for these bridges - as already noted - is their dy-namic behaviour. This behaviour can

be improved by an extra-wide deck, a streamlined deck cross section, a V-shaped arrangement of the hangers and by the placement of cable stays in the region near the pylons. In 1968, F. Leonhardt already emphasized the im-portance of a streamlined cross section and the effectiveness of V-shaped hangers [1]. References [2, 3 and 4] propose combinations of these mea-sures. Reference [5] proposes a con-cept with spread pylons for the suspen-sion cables, which most likely will pre-sent considerable difficulties in con-struction. New Structural System for Ex-tremely Long Spans In the following, a new, construction-ally simple and efficient concept for extremely long spans (or narrow, long span bridges) will be briefly intro-duced. As a basis for this proposal, a six-lane highway with two additional lanes for rail traffic is considered. The vertical load will be taken in large part by a more or less conventional suspen-sion bridge system. In place of the usual frame pylon, however, in consid-eration of the large dimensions for the cross section, a single central pylon is planned which is simpler to erect, more stable, and aesthetically satisfy-ing (Fig. 17). The dynamic stability of the bridge is assured by placing on ei-ther side of the deck girder a sloping cable-stayed system carried by slender pylons which are supported by the cen-tral pylon.

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Fig. 17

By means of a cable connection with the central pylon, the danger of buck-ling in the slender cable-stayed pylons will be practically eliminated. In the vicinity of the pylon, the cable-stayed system will also carry the vertical load; on the central part of the span the more widely spaced cable stays serve pri-marily for the dynamic stabilization of the deck. If the compressive force in the deck must be limited, then at least a part of the stabilizing cables can be anchored (like he suspension cables) in the ground (Fig. 18). The construction sequence for this sys-tem is relatively simple: – erect the central pylon – install the suspension cables (the most difficult process of the erection of the bridge)

– pull up the cable-stayed pylons. which are anchored with temporary and final cables to the central pylon – build the deck from the cable stays and the suspenders. The proposed concept considers nu-merous parameters, which for a bridge with an extremely long span, must he optimized specifically for each design. The following parameters are particu-larly important: – height of the central pylon, height and slope of the cable-stayed pylons – placement of the traffic lanes, rail . lines in the middle of the deck or placed one at each edge – number of suspension cables: two or three – form of the deck cross section and length of the deck segments – length of the region with V-shaped hangers – construction: installation of the sus-pension cables, erection of the deck. What Comes Next? At the present time, steel is clearly the most suitable material for 3000 m spans. This could change, however, if synthetic materials such as carbon fi-bers prove reliable in construction and the cost of their production were to de-crease substantially. For spans greater than 3000 m, new materials that are significantly lighter than steel are es-sential. As spans increase beyond 3000 m, it will become necessary to build an in-creasingly larger proportion of struc-tural components completely or partly of synthetics.

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Fig. 18

The first components to be built of synthetic materials will be long stabi-lizing cables. For these cables, the ideal axial stiffness, which is a func-tion of sag, is extremely important [6]. For long spans, lighter carbon fiber ca-bles can achieve the same stiffness with a much smaller cross section than heavier steel cables. As spans increase, it will become nec-essary to use synthetic materials for the main suspension cables. Already for 3000 m spans, the weight per unit length of suspension cables is roughly equal to that of the girder it supports. The unit weight of the cables should not increase as spans are increased even further. This can be avoided most simply through the use of a hybrid ca-ble system, in which cables are com-posed of synthetics and steel acting to-gether. Although the coefficients of thermal expansion are different for these two materials, the stresses redis-tributed from one material to the other

due to change in temperature are small compared to stresses due to load. The last step in the development of bridges of extremely long spans may be not only the entire cable system of synthetic materials, but also the girder. The first tests of girders made of syn-thetics are already under way [7]. The proposed basic structural concept for the design and construction of the tow-ers would remain valid in such a case. Concluding Remarks Simple extrapolations of rather con-ventional concepts usually do not lead to great progress in technological de-velopment. This is true as well for ex-tremely long spans in bridge structures. Because today lightweight high strength materials are not yet inexpen-sive and cannot yet be produced in suf-ficient quantity, economical and prac-tical designs for extremely long spans require unconventional structural sys-

164

tems. The proposed structural concept, with its relatively simple construction technique, is certainly suited for this design problem. It is suitable, not only for great spans but also for narrow bridges with shorter spans and espe-cially also for long span pipeline bridges. References [1] LEONHARDT, F. Zur Entwicklung aerodynamisch stabiler Hangebrii-cken. Die Bautechnik 45, Heft 10 und 11,1968. [2] LACROIX, R., et al. 3000 Metres: We Can Make It! Proc. Int. Conf. IABSE-FIP, Deauville, 1994, Vol. 1, pp. 505-515.

[3] CASTELLANI, A. The Project for the Bridge over the Messina Strait, ibid., pp. 517-527. [4] WALTHER, R., AMSLER, D. Hy-brid Suspension Systems for Very Long Span Bridges: Aerodynamic Analysis and Cost Estimates, ibid., pp. 529-536. [5] GIMSING, N.J. Suspended Bridges with Very Long Spans, ibid., pp. 489-504. [6] MEIER, U. Carbon Fiber-Reinforced Polymers: Modern Materi-als in Bridge Engineering. IABSE, Zu-rich, SEI1/1992, p. 7. (7) SEIBLE, E, BURGUENO, R. Ad-vanced Composites in Cable Stayed Bridges. Seminar in Cable-Stayed Bridges, Miami, FL, Oct. 17-18,1994.

WEST SEATTLE SWING BRIDGE, SEATTLE, WASHINGTON John H. Clark, Vice Pres., Andersen Bjornstad Kane Jacobs, Inc., Seattle, WA Planning A double-leaf concrete swing bridge across the Duwamish River in Seattle, Washington, represents a revival of a type of movable bridge long out of fa-vor and incorporates new concepts in machinery and movable bridge tech-nology. The bridge connects two por-tions of the industrial port area of Seat-tle across one of its major shipping channels. Prospects for widening the current-46 m wide ship channel to 76 m required replacement of an existing bascule, built in 1927. Navigation traffic in 1994 required approximately 10 open-

ings per day of the existing bridge, which provides 14 m of vertical clear-ance over high water. Increasing the vertical clearance from 14 m for the existing bascule bridge to 17 m for the new bridge was predicted to be suffi-cient to reduce the number of openings to 7 per day average, primarily for large ocean-going barges and ships. Roadway traffic is predicted to reach 11000 vehicles per day, with approxi-mately 15 % truck traffic. Pedestrians and bicycles are also pro-vided for on the new swing span, but are excluded from the high level bridge. The total structure width of 15.2 m provides for two traffic lanes and one combined bicycle/pedestrian way 3.66 m wide.

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Fig. 19The swing bridge alignment was placed on the existing bridge align-ment to minimize required right of way and revisions to the existing street network. This alignment results in the bridge axis being skewed approxi-mately 45° to the channel. A total of nineteen different alignments and three basic structure types were evaluated before selection of the swing bridge for final design development. Other struc-ture types investigated in the prelimi-nary design stages were a vertical lift bridge and a bascule bridge. The 146 m span center-to-center of pivot piers (Fig. 19) for the swing bridge was established by the width of the open west leaf and the location of a column of the adjacent high level bridge. The east pivot pier is then placed symmetrically about the center-line of the proposed channel. The tail span length of 53 m was also set by the column of the high level bridge. Once

the alignment was chosen, the span lengths were fixed. The west approach length of 153 m is determined by the need to cross over a railroad track and an intersecting street. The east ap-proach length of 147 m was deter-mined by the maximum grade of 7% and vertical curve lengths required for proper sight distance. Stair towers for pedestrian access are provided on each approach. A control tower for the bridge operator is adjacent to, but sep-arate from, the west pivot pier. The control tower is a 36 m high structure, so that the bridge operator has unre-stricted view of the channel and all of, the approach roadway. Structural Design The crossing site is near the mouth of the Duwamish River. Soils encoun-tered at the site range from hydraulic fill and recent alluvial sands and silts

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to heavily pre-consolidated glacial till. Depth to the till varies from 15 m on the west end of the project to 60 m on the east end. Lenses of loose silt exist erratically throughout the alluvium layer. The loose surficial silts and hy-draulic fill are deemed susceptible to liquefaction in major seismic events. Densification by vibro-flotation was specified to prevent such liquefaction. Seismicity in the area is moderately ac-tive. Seismic design criteria generally followed the Guide Specifications for Seismic Design of Highway Bridges, 1983, of the American Association of State Highway and Transportation Of-ficials, with appropriate modifications for the unique structure. The basic seismic coefficient, amax is 0.30 g and the soil type is Type III. The main piers and superstructure comprise a structural unit which does not contain the "ductile element" upon which the Guide Specifications are

Fig. 20

based. The location of the piers in the sloping bank of the existing and future channel created a problem of differing

transverse stiffness of the piles which would have led to eccentricity between the center of mass and center of rigid-ity. These two problems were ad-dressed by the new concept of "seismic isolation" sleeves. Considerations in the choice for the superstructure design were construc-tion economy, maintenance costs, traf-fic safety and aesthetic compatibility with the adjacent high-level bridge (a concrete box girder). Two designs were prepared and advertised for bids, a post-tensioned segmental concrete box girder and a steel box girder with a precast prestressed concrete deck made composite after erection. Typical cross sections of the concrete alternative are shown in (Fig. 20). A major challenge in the design of the concrete box girder bridge was control of long-term deformations. Provisions for control of both long-term and short-term deformations included ad-ditional post-tensioning beyond that required for stress control, provision of some unbonded tendons, provision for additional future tendons, provisions for adjustment of approach span eleva-tion at the tail span joint, provision for vertical adjustment of each leaf as a whole, and specifications requiring nearly simultaneous construction of the two movable leaves. The first line of defense against un-wanted long-term deformation was the adoption of the principle of load bal-ancing for the design of the longitudi-nal post-tensioning. The amount of prestress provided is the amount re-quired to provide 100% load balancing for the final dead load condition. This

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required approximately 30% more post-tensioning than the amount re quired to satisfy service load stress conditions. The deck of the box girder is post-tensioned transversely and ver-tical post-tensioning is included in the webs. The additional longitudinal post-tensioning reduced the need for verti-cal post-tensioning in some areas. Static balance of each leaf about the pivot pier is achieved by thickening the webs and bottom slab in the tail span and by the addition of ballast concrete and galvanized reinforcing steel bars such that the last 12 m of the tail span is solid except for an access shaft. As-built measurements were taken after

casting of each section so that the final static balance could be closely predict-ed. It was found necessary to explicitly account for the measured density of the concrete (from quality control test cyl-inders) and the actual weight of re-inforcing and prestressing steel in each segment to accurately predict the static balance. Allowable static imbalance during construction while the bridge rested on temporary service bearings was 72 MNm. Static imbalance during service operations of the movable leaves was limited to 6.8 MNm to avoid stick-slip chatter in the pivot shaft guide bearings.

Fig. 21

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Pier House and Machinery The 12.8 m diameter pier house carries the superstructure loads to the founda-tions and houses the drive machinery, emergency generators, and part of the control system. The pier table element of each leaf is supported by a transition element which provides two load paths to the foundation. The closed position path (serving vehicular traffic) is from the superstructure pier table through a conical shell to the walls of the pier house. Service bearings made up from steel plates with reinforced elastomers separate the transition element from the roof of the pier house. These ser-vice bearings are placed on an 11.4 m diameter circle. Temporary bearings were placed between the permanent service bearings to provide stability during construction of the cast-in-place segmental concrete leaves. The operating position load path is from the pier table through the center portion of the transition element to the 3.66 m diameter pivot shaft. The pivot shaft is a concrete-filled steel shell 44 mm thick which in turn rests on the hydraulically operated lift-turn cylin-der. The pivot shaft is maintained in the vertical position by guide bearings (Fig. 21) at the roof and operating floor level of the pier house. In the op-erating position, the whole movable leaf including transition element and pivot shaft are raised approximately 25 mm to transfer the load from the ser-vice bearings to the pivot shaft. A rein-forced concrete footing founded on 36

concrete filled steel pipe piles, 91 cm diameter, completes both load paths. Heavy locks at the tail span joint and at the center joint are provided for trans-fer of seismic response loads and to restrain differential displacements due traffic, differential temperature, and accidental misalignment. The torsional stiffness of the box section is suffi-ciently high that locks were provided only on the longitudinal centerline of the section. The locks are driven by hydraulic rams powered by local pumps. Twin hydraulic slewing cylinders (56 cm bore x 234 cm stroke) rotate each movable leaf from the closed position to the open position to allow for pas-sage of ships. The operational cycle is based on a normal two minute slewing time, total cycle including traffic lights and gates is approximately 4.5 min-utes. Friction is minimized due to the fact that the structure is supported on the hydraulic fluid of the lift-turn cyl-inder. The principal source of friction is the pivot shaft guide bearings which maintain vertical alignment. Power for raising and rotating the movable leaf is provided by 3-75 kW, 8-liter-per-second hydraulic pumps in each pier house. Normal operation is with two pumps, the third pump alter-nates as a spare. Other redundancies built into the system include the ability to slew the bridge using only one slew-ing cylinder (with increased cycle time) and even to slew the bridge against the friction of the service bear-ings, should the lift/turn cylinder fail to operate.

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Hydraulic system components are de-signed to operate at a normal pressure of 11.7 MPa and an emergency (slew-ing against the service bearing friction) pressure of 41.4 Mpa. The control unit is a programmable controller which sequences operations, and provides status information to the bridge operator. The primary position control is limit switches which initiate braking via the controller. The control system is essentially the same as man-ual operation except that the controller "pushes the buttons," checks inter-locks, and announces the status on a monitor. Manual override is possible for most steps of the operation. Diesel powered emergency generator sets (350 kW) are provided in each pier house on the lower floor. Fuel storage is placed in day tanks on the shore. Construction Costs Bids for the construction of the project were received in September 1988. Five bids were received for the concrete box girder alternative ranging from USD 33.5 to USD 37.6 million, including demolition of the south bascule, all ap-proach work and site work. The cost breakdown for major work categories (based on the low bid) is presented in Table 1. The contract called for a 22 month construction schedule.

Item Cost USD Millions

Mobilization 2. 80 Demolition 3.76 Civil: streets, utilities, traffic

3.38

Approach spans 4.66 Swing piers 6.87 Swing spans 5.60 Machinery 3.98 Electrical 1.06 Controls, control tower 0.94 Pier protection 0.48 Total 33.53

Table 1: Cost breakdown (low bid) Owner: City of Seattle, WA Design: Andersen Bjornstad Kane Jacobs, Seattle, WA Parson Brinckerhoff Quade and Douglas, Seattle, WA Tudor Engineering, Seattle, WA Contractor: Kiewit-Global Joint Venture, Seattle, WA Service date August 1992

PRECAST SEGMENTAL HIGHWAY VIADUCTS, HAWAII Gerard Sauvageot, Vice Pres. J. Muller International, San Diego, CA

General Description

Oahu Island, in the Hawaiian Islands, with the state capital Honolulu and the bay of Pearl Harbor, is presently expe-riencing significant new urban arid

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tourism development. To link the most populated areas of the south to the towns and military bases on the north-east, the Hawaiian Department of Transportation, with the financial sup-port of the US Federal Highway Ad-ministration, is building an extension of the H-3 Freeway across the steep and volcanic Koolau Mountains. Be-cause of its natural beauty and archae-ological significance, the whole area is very sensitive environmentally. From the vicinity of Pearl Harbor, the free-way includes the North Halawa Via-ducts, the Haiku Tunnels under the mountain range, and the Windward Viaducts on the north slope, where it will connect to the north end of H-3 al-ready in service The new Windward Viaducts consist of twin parallel prestressed concrete structures approximately 2 km long with 24 spans each. The maximum span length is 91.5 m and column height varies from 3.6 to 48.8 m. The width of each bridge varies from 12.8 to 17.4 m. The geometry of the via-ducts includes reverse curves with ra-dius varying between 470 and 753 m and cross slope between 5.5 % on one side and 6.8% on the other side. The longitudinal slope of the structure is about 5 %. The horizontal distance be-tween the structures is constant on most of the length at 21.3 m, but in-creases at one end where it connects to the two separate tunnels. Crosswise the elevation of the two parallel decks var-ies by as much as 4.6 m. Value Engineering Design The structure was designed as a vari-

able depth concrete box girder to be built in balanced cantilever with 4.9 m long superstructure segments cast in place with travelling forms. The struc-ture shown in the base design would have been supported by cast-in-place hollow concrete piers with a single row of fixed or sliding bearings at the top. The foundations consisted of 400 mm diameter, octagonal precast driven piles. After bidding on the base design, an alternate was proposed according to "Value Engineering" procedure, whereby certain economic and techni-cal conditions must be met, such as sharing any savings with the owner and retaining the appearance, geome-try, and alignment of the structure, which had been the object of a lengthy environmental impact assessment. The alternate design accepted by the contractors’ joint venture and the owner, included the following changes: - piers and superstructure were made monolithic - precast piles were replaced with 1.5 m diameter drilled shafts - precast segmental construction was used for the superstructure. The project specifications allowed 1360 days for the construction of the viaducts. This schedule did not provide additional time for rainy days, which are frequent on the windward side of the island. Precast construction has the advantage of decreasing the amount of work performed at the site, improving quality and speed of erection and sig-nificantly, allowing the superstructure

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to be entirely constructed from above in this difficult terrain. Each viaduct is a single box made of precast segments with vertical webs and parabolic intrados. The depth var-ies from 4.9 m at pier to 2.45 m at midspan (Fig. 22). The length of the precast segments are such that the maximum weight is 70 t. A 2-segment

expansion joint is located every four spans, at about one-quarter of the span. This disposition reduces deflections and changes of angle at the joint. The two hinge segments are temporarily prestressed and treated as one piece during the erection process. Tendons through the hinge are released after the next span is installed and stressed.

Fig. 22 The longitudinal post'-tensioning lay-out was conventional with straight 19 x 13 mm strand tendons placed within the top slab and anchored at the seg-ment joints, close to the top of the webs, 32 tendons were used in each typical cantilever. The continuity post-tensioning consists typically of 18-19 x 13 mm strand tendons placed in the bottom slab and anchored in concrete blocks. No draped tendons were re-quired in the webs, except for the hinge and abutment spans. Additional deviation blocks running from pier segment diaphragm to pier segment diaphragm provide for any future ex-ternal post-tensioning contingencies. A 75 mm thick reinforced overlay is ap-

plied to the bridge at the end of con-struction according to the original pro-ject specifications.

Erection System A special erection system was de-signed and used for this structure with a self-launching gantry that allowed both viaduct structures to be built si-multaneously. The system is designed to accommodate variable cross slopes, curves, differential elevations, and variable distances between the two structures. The system includes two independent erection trusses, steel support beams supporting the trusses, a gantry crane

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and lifting trolley. The gantry crane is supported by two trusses, one on each bridge. Transverse cross beams act as supports for the trusses. Each truss rests on three cross beams, one at the rear, at the tip of the previous cantilever, one on top of the pier segment of the can-tilever under construction and a third, mobile, on the front arm of the con-crete cantilever and supporting the truss as the construction progresses, reducing deflections and moments in the truss. This was possible because of the moment-resisting connection be-tween the deck and pier shaft. Each cross beam is set horizontally on the concrete deck. A gantry crane rolls longitudinally on the top members of the two trusses. The gantry crane carries a lifting trol-ley running transversely to the two trusses. The segments are delivered by truck at the extremity of the previous cantilever, picked up by the gantry crane/lifting trolley and delivered at either ends of the twin cantilevers un-der construction. The gantry crane is equipped with two legs on wheels. The leg on the mountainside truss is the "fixed leg." The leg on the ocean side truss is the pendulum leg. Each leg is built with the minimum degree of free-dom compatible with its motion and the stability of the gantry crane. The longitudinal displacement on top of the trusses is by a rack-and-pinion hydrau-lically driven system insuring total safety on the 5 % longitudinal slope of the bridge. The relative longitudinal motion of one leg with regard to the other (each leg running on one truss

26.2 m away) is entirely controlled by an electronic device monitoring the speed of the hydraulic motors and keeping the "lag" within acceptable tolerances. The launching of the trusses to the next pier is done by fixing the gantry crane to the concrete deck through a tempo-rary attachment and activating its hy-draulic motors which then push the trusses under the gantry instead of moving the gantry on the trusses. The trusses are launched one at a time to minimize the load on the cantilever. A complete launching from pier to pier took about 18 hours (Fig. 23). After completion of the learning curve, the contractor typically achieved the re-sults shown in Table 2. On the best day, the contractor was able to set 16 segments.

Fig. 23 The remarkable speed that this erection system is able to achieve is due to its separation of the two operations which were performed for each pair of seg-ments, i.e., placing and post-ten-sioning. During the operation of plac-ing a pair of segments, which included bringing the segments to the erection equipment, applying epoxy and tem-

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porarily stressing them on one can-tilever, the contractor was able to work simultaneously on the other cantilever to perform the post-tensioning opera-tion, threading of tendons and stress-ing. This made the whole erection process more efficient.

Task Days needed

Adjust 4 starter segments, pour closure joint, stress post-tensioning tendons

2.5

Erect two parallel cantile-vers

5

Pour central spans closure joint and stress continuity tendons

3

Launch trusses

2

Total

12.5

Table 2: Typical erection cycle Base design: Wilson Okamoto Associates, Honolulu, HI Contractor: SCI Contractors, Inc. and E.E. Black, Ltd., Joint Venture, Honolulu, HI Value engineering design: I Muller Int., San Diego, CA Launching truss design: J. Muller Int., San Diego, CA Engineer of Record: Libby Engineers, San Diego, CA H-3 Viaduct completed: 1993

TALMADGE MEMORIAL BRIDGE, SAVANNAH, GEORGIA Man-Chung Tang, Pres. DRC Consultants, Inc., Flushing, NY

Description The new Talmadge Memorial Bridge is a 2.31 km long high-level structure connecting the city of Savannah, Georgia, and Hutchinson Island over the Savannah Front River. It replaces an existing bridge which was hit by ships several times because its navi-gational clearance of 41 m was too low for today's ocean-going vessels. The new main river span now provides a navigational clearance of 183 m hori-zontally and 56.4 m vertically, which

will accommodate any ocean-going vessels today. The Talmadge Memorial Bridge is a three-span continuous cable-stayed structure with a center span of 335.4 m and side spans of 143.2 m, resulting in a 621.8 m cable-stayed unit. The main span length was determined by the de-sire to place the towers outside the channel to avoid ship collision. Design Alternatives To stimulate competition, the final de-sign consisted of two alternatives: a concrete proposal and a steel alterna-tive with a composite deck. The final designs were each executed by differ-

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ent firms. In order to accommodate the request of the owner to treat the main span and the approach spans as two separate entities for bidding purposes, the total length of the main span units for both alternates had to be identical. Since the center span was predeter-mined, the designers of the two alter-natives worked .together to determine the lengths of the side spans that was acceptable to both designs. All six bids received were for the con-crete alternate. The successful lowest bid price was USD 25.7 million. The approach span was bid at a later date under a separate contract. Aesthetics Due to its location, size and height, this bridge is a highly visible structure, dominating Savannah's river front. A slender appearance was deemed pref-erable, especially for the towers, which reach 122 m above the water. Many shapes for the towers were studied. The final shape selected demonstrates that a functional configuration that is economical to construct can also be aesthetically pleasing: The bridge is also dramatically illuminated at night. Design Loadings The bridge was designed for four lane loads according to AASHTO HS20-44. However, considering that live load generally dominates the design of a ca-ble-stayed bridge girder, no reduction for multi-lanes was applied. In effect this increased the actual design load to approximately the equivalent of six AASHTO lanes.

Calculation of the impact factor fol-lowed the AASHTO concept. The total loaded length was used. The impact was to apply to the design of the gird-er, the cables and the towers. In addition to the normal AASHTO wind loading, an additional load case of extreme wind was added because hurricanes are quite common at this site. For this static extreme wind load, w - q x c, q is assumed to be 3 kN/m2 at the deck level and varies to 4.0 kN/m2 at the top of the tower and to 1.5 kN/m2 at elevations below 9.1 m. The shape factor c was determined by wind tunnel tests. This extreme wind, how-ever, was not combined with live load in the design. Due to the sensitivity of cable-stayed bridges to differential temperature variations between the cables, the tow-ers and the deck, several additional thermal load cases were added to the AASHTO requirements. Savannah is not in a seismic active zone. However, a detailed dynamic analysis was car-ried out to ascertain the safety of the structure in case of a possible earth-quake nearby. A modal analysis with multiple support excitations was con-ducted and the results incorporated in the final design of the structure. A differential settlement of 15 cm be-tween the towers and the anchor piers was assumed in the design. In sum, the design criteria have been conservative-ly established to assure the safety and durability of the structure. Tower Due to its stiffness and ease of con-

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struction, a hollow cross section was selected for the towers. The size of the tower columns was determined by the requirements of strength and the space needed for cable installation. In gener-al, it is easier to stress cables at the tower anchorages because a jack can be suspended from the top of the tower column. A box configuration, with the cables anchored in the front and the back walls of the tower column, was chosen for simplicity. The cables are in the same vertical plane. This simplified the cable geometry and reduced the di-mensional control during construction. But cable forces anchored in one wall must be transferred and connected to the cable forces anchored at the oppo-site wall of the column. Post-tensioning bar tendons were used for this purpose to prestress all four walls of the tower column in the vicinity of the cable anchorages. Calculation of this force transfer was by means of a strut-and-tie method, neglecting all tensile capacity of the concrete. The design of the lower portion of the tower was controlled mostly by trans-verse wind loading. Design earthquake effect approached approximately the severity of wind. To assure the neces-sary ductility, tie reinforcement was placed at the bottom and the top of the lower tower legs. Deck Configuration of the bridge girder de-termines the method of construction. The basic design goal to make the cross section as simple as possible was successfully achieved in the Talmadge

Memorial Bridge. The deckwas not only easy to construct, it was also one of the lightest possible cross sections for a cable-stayed bridge The deck girder was designed as a re-inforced concrete structure, even though longitudinal post-tensioning was applied in some areas to help con-trol possible cracking, notably in the middle portion of the center span and the end region of the side spans, where axial compression induced by the cable forces was low. A preliminary conceptual design of the traveler was done during the design stage to establish its approximate weight and the feasibility of construc-tion. It was found that the traveler weight should be approximately 175 t, assuming that the front cable was used to support the traveler. With a well-de-signed traveler, the construction of the deck proved to be a straight forward operation. The floor beams were designed in pre-stressed concrete. Each floor beam was prestressed by two 19-0.6" strands. The spacings of the floor beams were exactly the same as the spacings of the cables. The floor beams were located as closely as pos-sible to the cable anchorage to reduce local bending moments in the edge girders. The slab was analyzed with due con-sideration of its nonlinear behavior due to the high compression in the bridge deck. The bridge girder was also de-signed to provide sufficient capacity for possible accidental failure of a stay cable. Under this emergency condition

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the deck had to be able to safely carry a reduced live load. Cables Two types of cables were considered in the design: parallel wire cables and the seven-wire strand cables. Due to the difference in the stiffness of these two types of cables, the structure was analyzed for both types in order to as-certain that selection of either type would be satisfactory for the structure. The performance requirement of the cables basically conformed to the rec-ommendations of the American Post-Tensioning Institute. In addition, the strand anchorages were also tested for fatigue loading without grout in order to assure the effectiveness of the cables under the unlikely condition of defec-tive grout in the anchorage. Construction Construction of the deck girder was by means of a cable-supported form trav-eller. The contractor added water bal-last to the traveler. This was to allow the stressing of the cables to a higher force before the concrete was cast. The water ballast was released as fresh concrete was poured in a segment. This increased the weight of the travel-ler to over 2001. The contractor elected to use the seven wire strand alternate for the cables. The "Stronghold" system was success-fully tested according to the specifica-

tions at the University of Munich, Ger-many. The strands were installed one at a time and first anchored by means of a mono-strand jack. The entire cable was then stressed using a single large multi-strand jack. All jacking was done from the tower end. The strands were placed inside plastic pipe. The space between the pipe and the strands was grouted with cement grout. The pipes were wrapped with white tape to give extra protection and to reduce the cables' temperature. Be-sides, the white color enhanced the ap-pearance of the bridge. As specified in the bid document, the contractor hired a consulting engineer to provide the construction engineering for the bridge. The submission was re-viewed in detail by the owner's in-house engineers and by the designer to assure that the construction met the in-tent of the design. In addition, the de-signer was represented at the site to as-sist the owner in quality control of construction. Owner: City of Savannah, GA Design engineers: DRC Consultants, Inc., Flushing, NY Construction engineers: Buckland and Taylor, Vancouver, BC, Canada Main contractors: Monterey Inc., San Francisco, CA Groves Inc., Minneapolis, MN Service Date: 1990.

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ACOSTA BRIDGE REPLACEMENT, JACKSONVILLE, FLORIDA Brett H. Pielstick, Civil Eng. Steinman, Boynton, Gronquist & Bird-sall, Daytona Beach, FL Project Description The new Acosta Bridge is a USD 148 million project crossing the St. John's River in downtown Jacksonville, Flor-ida. This project features twin five-span structures, each totalling 501 m in length. Cast-in-place segmental con-crete box girder construction was used throughout with the exception of the approach spans. The asymmetrical main span of 192 m was built by balanced cantilever con-struction with traveling forms. The ap-proach spans for the river crossing were constructed span-by-span on fal-sework. The approaches and corre-sponding ramps to the river bridge were constructed of steel plate and box girders. The project was designed to be con-structed in three separate stages in or-der to maintain the flow of traffic and limit the amount of additional right of way required for the new structure. Stage one involved the construction of the eastern three lane bridge, while traffic was maintained on the old Acosta Bridge. Stage two involved the placement of traffic on the new eastern three lane bridge, allowing demolition of the old crossing which lay between a railroad bridge and the new bridge. The third and final stage of construc-tion entailed maintaining traffic on the

new eastern bridge and constructing the western bridge. Scour Protection As downtown Jacksonville grew, more land was created by filling the St. John's River in areas adjacent to the Acosta Bridge. The substantial reduc-tion in river area created a scour con-dition that removed over 10 m of ma-terial from areas around the founda-tions of the old bridge. Several founda-tions of the old bridge had only 0.6 m of embedment remaining at the time of demolition. After the superstructure of the old structure was removed, stability cables were required to keep the old columns from falling over. Gabion mats were used to combat the extreme scour conditions around the old Acosta Bridge, the 60 year old rail-road bridge, and the new Acosta Bridge. These 4.9 m x 11.0 m mats were constructed using PVC-coated, chain link fabric mesh mattresses filled with rock to a thickness of 230 mm. The gabion mats were placed in layers on the river bottom arid laced together underwater. Rip-rap and filter fabric were placed around piers and drilled shafts to provide continuity of the scour protection system. Foundation and Substructure The new Acosta Bridge is supported on 1.5 m diameter drilled shafts with 7 to 8 shafts per back span support, and 31 and 22 shafts for each of the two

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main piers making a total of 82 shafts per bridge. An extensive test program utilizing 900 mm test shafts was used to check capacities. Testing involved the use of sister bar strain gauges, Os-terburg cells, telltales and a wire line to measure stresses and movements. The use of the Osterburg hydraulic cell was innovative for this type of equipment, being applied in a silty clay marl to de-termine end bearing capacity. Waterline footings were constructed on the drilled shafts using a ring support bolted to each drilled shaft. With the rings in place, a 230 mm thick precast seal slab was set. A top yoke support system was then used to support the footing side forms. A 460 mm to 530 mm seal was then placed, enabling the removal of 1 m of water from the forms. The footing, column and cap were then constructed with conven-tional cast-in-place methods. Due to physical restraints, and in an ef-fort to minimize the size of the founda-tions, the designer used pot bearings to support the bridge at all pier locations. The larger of the two cantilevers was erected on three 53.4 MN fixed pot bearings. The second antilever bearing system consists of three guided 38.7 MN pot bearings and are among the largest bearings of their type in North America. One of each of these large bearings was tested at the US National Testing Laboratory near Washington, DC. The cantilevers were erected by bal-anced cantilever construction. The can-tilever was limited to about one-half of a segment out of balance through the

entire casting process to minimize the unbalanced moments. A stability system was required to sup-port the out of balance moment. This system consisted of three 1.1m diame-ter concrete filled steel pipes with 15.9 mm walls. One support was located under each web of the box. Grout pads on the footing provide lower support for this system. These pipes served as compression posts on each side of the column 4.9 m from the center of rota-tion. At the top of each post, a sand jack with a concrete wedge was placed to provide the connection under the pier table bottom slab. Superstructure The river crossing is a five-span con-tinuous structure composed of a 67 m back span, 110 m side span, 192 m main span, 83.8 m side span and a 48.8 m back span. The superstructure util-ized cast-in-place segmental con-struction with a typical box section measuring 23.10 m wide at the deck (Fig. 24). The box girder out-to-out width of 14.94 m consists of two cells and three web walls. The depth of the boxes varies from 3.66 m at mid-span to 11.58 m at the main pier table. A typical segment pour was 4.9 m long. The casting cycle was five days per traveller. Segments were post-tensioned once the concrete reached 24.13 MPa of the 37.92 MPa 28-day requirement. Three tendons made of fifteen 15 mm diame-ter strands were stressed to about 3.1 kN each after casting each cycle. Four-strand transverse tendons spaced ap-

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proximately 760 mm were stressed during the same cycle. Vertical web shear reinforcement was provided by 31.75 mm post-tensioning bars. To speed up construction, the contrac-tor varied from the designer's erection procedures and built the back spans on falsework. This allowed the cantilever construction to go on independent of the back spans. The resulting time sav-ings exceeded 16 weeks.

Fig. 24 Vibration Limits One of the greatest concerns in the project was the 60 year old railroad bridge located about 12 m to the west of the old Acosta Bridge. Historical levels for service vibrations were re-corded by instrumentation placed on

the old railroad bridge. Based on the recorded information and current blast literature, a blast limit was set for the railroad bridge at 101 mm/s peak parti-cle velocity. Throughout the blasting, monitors were placed on the railroad bridge and the new Acosta Bridge to measure the particle velocities. As the blasting pro-gressed, the blaster was able to use this information to set off more than 635 kg of explosive powder in one blast and remain within the peak particle ve-locity limits established for the project. Owner-Florida Department of Trans-portation Construction Engineering and Inspection: Steinman Boynton Gronquist and Birdsall, Tallahassee, FL Contractor: Recchi America, Miami, FL Engineers of Record: DRC Consultants, Flushing, NY Fred Wilson & Assoc, Jacksonville, FL Service date: July 1994

THE NORMANDIE BRIDGE, FRANCE: A NEW RECORD FOR CABLE-STAYED BRIDGES Michel Virlogeux Prof., Ecole Nationale des Ponts et Chausees, Paris, France Landmark Cable-Stayed Bridges On August 8, 1994, the last steel plate was welded to close the main span of

the Normandie Bridge, which, at 856 m, is the longest cable-stayed span in the world today (Fig. 25). The Nor-mandie Bridge will begin its service life in January 1995. This is an ap-propriate occasion to analyse its design and review the experience gained dur-ing the construction thus far.

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In the 1970s and '80s, it was generally considered that 500 m was a limit for cable-stayed bridges, and almost all projects were conceived with such a limit in mind. Consequently, the record span progressed slowly: 404 m in 1975 (Saint-Nazaire, France), 430 m in 1983 (Barrios de Luna Bridge, Spain), 465 m in 1986 (John Frazer Bridge to Anacis Island, Canada) and 490 m in 1991 (Ikuchi Bridge, Japan). But engineers already had some indi-cations that cable-stayed bridges were very far from their limits: three major bridges had been built in Germany with a single pylon: the Koln Severin Bridge (302 m in 1959), the Diissel-dorf Kniebrucke (320 m in 1969) and the Diisseldorf Flehe Bridge (368 m in 1979). For those who could foresee it, these three bridges proved that spans of 600-700 m could be built from two pylons without major problems. Some projects had been studied with long spans, but the bridges had not

been erected at the time: a first design was done for the Normandie Bridge between 1976 and 1979, with a main span 510 in long; and a cable-stayed solution was proposed in 1978 for the Eastern Bridge of the Storebaelt, Den-mark, with a span of 780 m. Fritz Leonhardt proposed a cable-stayed solution in 1968-1970 for cross-ing the Messina Straits with two py-lons in the sea and a main span 1300 m long. He was followed by Rene Walther, who proposed that concrete cable-stayed bridges can be economi-cally built up to 600 m, and composite ones up to 800 m. Recent Progress The preliminary design of the Nor-mandie Bridge - called the Honfleur Bridge at the time - was developed be-tween September, 1986 and Spring, 1987. The project was presented in the first conference devoted to cable-

Fig. 25

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stayed bridges, in Bangkok, in Novem-ber 1987. Since that time, the world record pro-gressed with two bridges designed and built very quickly, probably helped by the Normandie Bridge project, which psychologically opened the way for very long spans: the Skarnsund Bridge in Norway (530 m in November, 1991), and the Yangpu Bridge in Shanghai, China (602 m in October, 1993). Two other projects were clearly inspired by « the Normandie Bridge: the Honshu Shikoku Bridge Authority decided, after the Bangkok Confer-ence, that the Tatara Bridge would not be a suspension bridge, but a cable-stayed one. Its erection began in 1993, and it will become, in 1998 or 999, the new world record with its main span 890 m long. Danish engineers designed a new cable-stayed solution for the East Bridge of the Storebaelt, extend-ing the main span to 1200 m. All prob-lems found appropriate solutions, illus-trating the fantastic possibilities of ca-ble-stayed bridges, but navigation re-quirements finally called for a 1624 m long main span, longer that the longest suspended span in the world, and the cable-stayed solution was abandoned. It is now interesting to compare the cable-stayed bridges which held the successive world records: - Saint-Nazaire Bridge, 1975: steel orthotropic box-girder ... - Barrios de Luna Bridge, 1983: prestressed concrete bridge - Anacis Bridge, 1986: composite deck with two I-shaped beams and a concrete sfab - Ikuchi Bridge, 1991:

steel main span (and concrete access spans, like the Normandie Bridge) made of two parallel box-girders - Skarnsund Bridge, 1991: prestressed concrete - Yangpu Bridge, 1993: composite construction - Normandie Bridge, 1994: steel orthotropic box-girder for its main span. The cycle is closed, and a concrete ca-ble-stayed bridge with a main span of about 1000 m cannot be expected; nor probably a composite one due to high-er weight and increasing costs of ca-bles. But the competition which exist-ed during twenty years between con-crete, composite and steel decks is an-other indication that the limits have not have reached. Main Aspects of the Design While the Normandie fridge is likely be surpassed by even longer bridges in the years to come - the Tatara Bridge and still longer ones very soon there-after - it is of major importance in the technical evolution of long-span bridges. It is the first cable-stayed bridge entering the domain of very long spans, which was reserved up to now for suspension bridges. For this reason, it is worth pointing at the most important aspects of its design. Wind-Governed Design The design of long span bridges is governed by wind and wind effects. The Normandie Bridge helped or in-spired the design of other bridges, and

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it is also true that the Normandie Bridge itself was very much inspired from the suspension bridges designed by Freeman Fox and Partners: UK's Severn Bridge and Humber Bridge, and Turkey's first Bosphorus Bridge. As Klaus Ostenfeld once remarked when discussing the new cable-stayed solution for the Storebaelt in Denmark, "Engineers are climbing over each other's shoulders." The main aspects of the wind design of the Normandie Bridge are: - The streamlined cross section of the deck, to reduce wind forces and to in-crease the aerodynamic stability of the bridge. The streamlining is clearly in-spired from the English bridges men-tioned above, but the final shape was selected for specific reason: it had to be adapted to both concrete and steel structures, since the deck is in prestressed concrete in the access spans (Fig. 26) and in steel in the cen-tral part of the main span (Fig. 27).

Fig. 26

Fig. 27

- A high torsional rigidity, to clearly separate the vibration periods in tor-sion and vertical bending. For this rea-son, the deck is a box girder suspended on both sides. In addition, the pylons have the shape of an inverted Y to concentrate the higher anchorages of ables on the bridge longitudinal axis. - The shape of the pylon - an inverted Y - is also extremely efficient at resist-ing transverse wind forces (Fig. 28).

Fig. 28

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- The concrete and steel composite deck, with concrete access spans on close supports extended at a distance of 116 m from each pylon in the cen-tral span, as well as the rigid connec-tion between deck and pylons, in-creases the structure's rigidity. Wind-induced deflections are drastically re-duced. Alan Davenport compared the deformability of the Normandie Bridge with the Littlebelt suspension bridge - also efficiently built with a streamlined deck based on the English experience and a main span of only 600 m - and concluded that the Normandie Bridge behaves like a cable-stayed bridge with a much shorter main span and is much more rigid than a suspension bridge with a span of 500-600 m.

Fig. 29

Composite Construction The second major point in the design of the Normandie Bridge is the combi-nation of prestressed concrete and steel. Composite designs, where con-crete and steel are used to their greatest efficiency, are strongly endorsed by the designers of the Normandie Bridge. The Normandie Bridge combines con-crete and steel for the design of the deck, prestressed concrete in the access spans, on close supports, with an ex-tension in the main span on both sides. Only the central part of the m, in span is an orthotropic steel box girder, much lighter (9 t/m, instead of the usual 45 t/n) to limit the cable size. The use of concrete in the access spans reduces total costs and increases the bridge's rigidity, as well as the back staying ef-ficiency of all rear cables. This efficient combination of concrete and steel in cable-stayed decks had been used before for the design of the Tampico Bridge in Mexico (360 m, 1988) and of the Ikuchi Bridge in Ja-pan (490 m, 1991). And prior to that, much valuable experience had been gained about using various materials, such as traditional and lightweight concrete, in Dutch bridges built by the cantilever method (Nijmegen bridges, around 1970). The experience gained in using different weights for a specific structural purpose proved to be ex-tremely useful (the bridges at Ott-marsheim and Tricastin and the cable-stayed bridge over the Elorn River). The Normandie Bridge also uses a composite design for the upper part of the pylons, where cables are anchored (Fig. 29). It is far more efficient to de-

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sign a steel anchorage box to anchor the cables, since steel plates easily car-ry tensile stresses from back-stays to cables suspending the main span. In addition, it is much easier to fabricate these steel anchorage boxes - or the elements which will constitute them - in a factory than on site in concrete 100 or 200 m above ground. To achieve the proper geometry, it is nec-essary to precisely adjust the position of steel elements ants which are later completed by concrete walls. Probably the first application of this technique was in Belgium, for the con-struction of the Ben Ahin and Wandre Bridges, designed by Rene Greisch ond Jean-Marie Cremer. The idea was used again for the Evripos Bridge in Greece and for the Chalon-sur-Saone Bridge in France. The problem was more complex in the Normandie Bridge, with the transverse inclination of cables. A design was developed with Jean-Claude Foucriat, introducing horizontal prestressing tendons to press the concrete walls against the steel an-chorage boxes to help the transfer of vertical forces from steel to concrete. The steel anchorage tower was divided into 21 elements (the lower one being divided into two half-elements) to be lifted by the site crane (capacity: 20 t), and welded on site. The typical ele-ment was designed to anchor a pair of cables on each side. The main plates were divided in ties for the transfer of forces from the main span to back-stays in order to lighten the elements, reduce in situ welds and facilitate ac-cess from the lateral cells of the pylon - with a lift - to the anchorages.

High Performance Concrete The main advantage of high perfor-mance concrete for standard and me-dium span bridges is substantially en-hanced durability. But for heavily loaded elements, such as the pylons of cable-stayed bridges with long spans, or the concrete deck of the Normandie Bridge, which has to balance high stresses from wind effects, high perfor-mance concrete has great structural advantages. All concrete on the Normandie Bridge contains silica fume for a characteristic strength of 60 MPa. This allowed for a reduction in the cross section of the concrete in the pylons and deck and thus a reduction in weight and founda-tions. Erection of the Access Spans The erection of access spans on both banks required the contractors to de-velop a new technology. Classical erection techniques, with Teflon pads, would have produced very significant horizontal forces due to friction (up to 5%) and to the slope of the access ramp (6%). For this reason the initial design did not use the incremental launching method, although it was of great interest due to the complex cross section shape and to the high rein-forcement ratio necessary to resist wind forces. To be able to use it despite the slope, the contractors invented a so-called «staircase» method for horizontal span launching. The deck is supported on

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each pier by two trapezoidal blocks - one on each side - which can slide horizontally on the pier. This move-ment is permitted by special bearings, made of a series of small rollers, on top of the pier. After the forward movement, the deck is lifted by jacks commanded from a central computer and the trapezoidal blocks are pushed backwards, ready for a new launching step. The launching operation proceeds by successive launching steps: 15 cm horizontally and then 9 mm vertically to correspond to the slope of 6%. Such a procedure was only made pos-sible by the use of a series of sensors, to control horizontal and vertical movements on all supports, and of a central microcomputer which could command horizontal and vertical movements. It was of special impor-tance, of course, that vertical move-ments be the same on all supports at any time. In addition, this new technique reduces the necessary manpower during launching, since control is only n nec-essary at supports, which can be dome at the central command from, meas-urements obtained by sensors or video cameras. Erection of the Main Span The 116 m long concrete cantilever which extends the side spa is in the main one on each bank, and the 96 m long last side span have been built by the balanced cantilever method from the pylon with the help of temporary stays. In the last side span, the closure was made 6 m before r 'aching the

pier with the incrementally launched typical spans. The steel part of the main span, 624m long, has been erected by the cantile-ver method from the completed access spans with the help of a mobile derrick to lift the successive segment 19.6 m long, on each bank. A New Generation of Cables The preliminary design called for locked coil cables, which were consid-ered very well adapted to such long spans, but which arc unfortunately very heavy. Their erection cost thus proved prohibitive. For this reason, the contractors pro-posed alternative cables made of indi-vidually protected strands of hot-dip galvanised wires which were re-drawn to keep all their structural characteris-tics. After coiling and after the corre-sponding thermal treatment, the voids between wires were filled with oil wax to repel any water. The strand was then protected by extruded high density polyethylene at least 1.5 mm thick. These strands were placed and ten-sioned one-by-one. Individual place-ment was extremely economical, but tensioning required a new technique, already developed by the cable sup-plier for the erection of three bridges: the Arrade and Guadiana Bridges in Portugal, and the Chalon-sur-Saone Bridge in France. The fast strand of each cable is tensioned to a computed value and equipped with a pressure cell which gives the tension at any time. Each new strand, when installed, is tensioned to have exactly the same ten-

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sion as the pilot strand at that precise moment, which is given by the cell. All strands thus receive the same ten-sion, which is the desired one if the initial tension of the pilot strand had been appropriately computed. If not. an adjustment is made the same way. This process is not susceptible to influ-ences from temporary operations, such as the movement of construction equipment. Finally, cables received an external duct made of a series of two half-ele-ments which are forced into each oth-er. These ducts are not for corrosion protection; they are air and water per-meable. They aim at reducing drag forces and avoiding rain-induced vi-brations of the cables. In addition, they totally eliminate the vibrations of strands in the bunch which makes each cable, which are produced by wind in-teraction between strands by a kind of "wake" effect. Interconnecting Ropes In his design for the Messina Straits, Fritz Leonhardt envisioned connecting all cables in each plane of the cables by tying ropes, which aimed at increas-ing the apparent modulus of elasticity of the suspension, lowered by sag ef-fects in long cable-stayed spans. In some other bridges, such as the Faro Bridge in Denmark or the two cable-stayed bridges of the Kojima-Sakaide route of the Honshu-Shikoku link, ropes were, installed to limit cable vi-bration which was rain-induced in the Faro Bridge and coming from the wake effect in the Japanese bridges.

The purpose is totally different in the Normandie Bridge: due to the very, long span of the bridge, the main vi-bration period for vertical bending would have been of the same magni-tude as the vibration period of the longer cables, 4.5 s, compared to about 4.0 s. In this situation, it was feared that cable vibrations would be induces by the deck movements. Interconnect-ing ropes were designed to totally change the vibration periods of cables, at least transversally, reducing them to 1.25 s and less. Four ropes connect all cables in each plane of stays. Their tension was se-lected to avoid de-tensioning from vi-brations produced by wind turbulence. Their constitution is composite, with steel and plastic to increase fatigue re-sistance because it is obviously diffi-cult to simultaneously achieve a high damping coefficient and a high fatigue resistance. Concluding Remarks The design and construction of very large bridges which go beyond existing limits require the strongest determina-tion from the Owner, who must invest enormous confidence in, and support of, the engineers in charge. The most dangerous tempests that audacious pro-jects face are not produced by wind on site, but by antagonistic opinions that find a willing audience. The success of the Normandie Bridge is due in large part to the confidence and support that the project received from the Owner, the Road Director and the local authorities. Some organi-

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sational aspects and some episodes during construction indicate the deci-sive importance of human factors. The Owner gave the design engineers total responsibility for the design and granted them complete freedom to as-semble the design team. Under these circumstances, improvements could be introduced at each step of the project, with no consideration other than effi-ciency. This is far superior to design competitions, now preferred by some administrations, where projects can be selected based not always on structural ; aspects, and where designers can be-come prisoners of their initial sketches and of premature options and deci-sions. Although there was no public money in the Normandie Bridge, the French government had to approve the project. The Road Director at the time, lean Berthier, decided to invite an as-essment of the design by an interna-tional group of experts: Marcel Huet (Project Manager of the Tancarville Bridge), Henri Mathieu, Charles Bngnon, Roger Lacroix, Rene W'alther and Jorg Schlaich. This group pro-posed various amendments, some of which were included in the final de-sign. Nevertheless, some engineers from one of the erection contractors considered the wind forces to have been un-derestimated and, thus, the safety ques-tionable. The debate became public, even international.

The Owner and the Road Direc-tor decided to consult Alan Davenport to evaluate the wind tunnel tests and the estimated wind forces. He ap-

proved the performed analyses and recommended some additional wind tunnel, tests, the results of which were even more favourable than the first evaluations. This confirmation of the design helped the project very much, and from the summer of 1991, all con-tractors worked with enthusiasm and energy to complete the bridge on schedule, within budget and up to the prescribed standards of quality. Any decision can be questioned, any action criticised. The clear conclusion is that a complex and ambitious project like the Normandie Bridge cannot be successfully realised without a strong Project Manager - as Bertrand Derou-baix has been for this project -to guide it over the years from conception to completion, even when questioned from many sides. Going further than ever before in any given field calls for courage. The Owner and the local au-thorities remained totally confident in the design and in the engineers in charge, even in difficult times. This was decisive for success; complex structures cannot be built with hesita-tions and doubts! References [1] VIRLOGEUX. M.; FOUCRIAT, J.-C; DEROUBAIX, B. Design -of the Normandie Cable-Stayed Bridge near Honfleur. Proc. of the Int. Conf. on Cable-Stayed Bridges, Bangkok, pp. 1111-1122, November, 1987. [2] V1RLOGEUX, M. Projet du Pont de Normandie, Conception generate de I'ou-vrage. Proc. of the 13th IABSE

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Congress, Helsinki, IABSE, June, 1988. [3] DEROUBAIX, B.; VIRLOGEUX, M. Design and Construction of the Nor-mandie Bridge. Proc. of the IABSE Symposium, St Petersburg, Russia, September 1991. [4] VIRLOGEUX, M. Wind Design and Analysis for the Normandie Bridge. In: 'Aerodynamics of Large Bridges,' A. Larsen, ed. Balkema, Rot-terdam 1992, pp. 183-216. [5] VIRLOGEUX, M. Normandie Bridge: Design and Construction. Proc. of the Inst. of Civil Engs, Struc-tures and Buildings, August, 1993, pp. 281-302. [6] DEROUBAIX, B. Presentation du projet et developpement de la constructio . In: Le point sur le Projet du Pont de Nor mandie. Annales de 1'ITBTP, Paris, September-October 1993. [7] LEGER, P. Finaiicvment du Pont de Normandie. ibid. [8] DAVENPORT, A. Analyse des etudes des effets du vent sur le Pont de Normandie. ibid.

[9] VIRLOGEUX, M. Le projet du Pont de Normandie. ibid. Owner: Chambre de Commerce et d'lndustrie du Havre Project Management: Mission du Pont de Normandie Design: SETRA, Sofresid, Quadric, SEEE, So-gelerg, Setec and Europe-Etudes Gecti. Architect: Charles Lavigne Wind Laboratories: CSTB and ONERA Contractors (concrete): GIE du Pont du Normandie (Bouygues, Campenon Bernard, Dumez, GTM, Quillery, Sogea. Spie Batignolles Contractors (steel): Monberg and Thorsen Sub-contractors: Bilfinger -\ Berger, Freyssinet, Munch, Lozai,VSL, SDFM Service date: January 1995

THE RAINBOW BRIDGE, JAPAN Kazuo Yamazaki, Mgr, Design and Research Div. Kimihiko Izumi, Mgr,

Design Div. Mitsunobu Ogihara, Chief, Design Div. Metropolitan Ex-pressway Public Corp., Tokyo, Japan

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Introduction The Rainbow Bridge has become a new landmark in the Port of Tokyo. The bridge provides direct access be-tween central Tokyo and a waterfront development now under construction. It also connects two expressways on both sides of the Port, creating the first express route across the city and is ex-pected to significantly ease traffic con-gestion in the centre of Tokyo.

The bridge is a 3-span, 2-hinge stiffen-ing truss suspension type with a centre span of 570 m and a total length of 798 m (Fig. 30). It has a double deck con-struction: the upper deck carries two two-lane expressways while the lower carries two two-lane roads serving the Port, as well as a railway and footpaths (Fig. 31). The diameter of the main cable is 762 mm.

Fig. 30 The bridge is founded on mudstone (consolidated silt or soft rock) far be-low the surface. Few suspension bridges- have their foundations on mudstone and several innovative tech-nologies were employed to overcome this unfavourable condition. Planning A suspension-type bridge was selected for the Port of Tokyo crossing to satis-

fy three significant constraints: - 500 m wide ship access with 50 m clearance - main tower height, including erec-tion equipment, of less than 155 m due to the proximity (9 km) of Haneda International Airport. - limited length for the side spans to link up with existing expressways on both sides of the bridge. A cable-stayed bridge could have been considered for the 570 m span, howev-

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er the height of the towers for this type of design would have been about 200 m. Besides, a cable-stayed design would have suffered excessive nega-tive reaction (uplift) at the link shoe of the side spans. For these reasons and economic considerations, a suspen-sion-type bridge was determined to be the best choice.

Fig. 31 Substructure The water depth at the site is approxi-mately 12 m, and the subsurface ground consists of a weak alluvial clay layer on top of a mudstone stratum. The mudstone bearing layer was found at levels between -30 and -38 m. Pneumatic caisson foundations were designed and constructed for the two main towers and the two anchorages.

The anchorage caissons are 70 m X 45 m. One anchorage caisson v as con-structed at sea using a steel box cais-son prefabricated in a shipyard; the other was constructed on land. For the pneumatic caissons, robotic ex-cavation was employed. A computer-controlled caisson shovel was operated remotely using a video camera. Exca-vated materials were placed onto an automatic belt conveyer for removal. This method ensured worker safety and construction efficiency under the high atmospheric pressure (3.5 bar) in the caisson's chamber. In addition, special digging machines were used for the excavation of the hard mud-stone. Since an anchorage would be subjected to a huge eccentric force due to the ca-ble tension (230 MN) a precise pre-diction of long-term (100 years') de-formation of the mudstone bearing layer was essential) The initial predic-tion was modified repeatedly using a measured displacement at each con-struction stage, and the values obtained were considered in the design of the superstructure.

Item Content

Type of bridge girder Span layout

3-span, 2 hinged-stiffening truss, double- deck suspension Stiffening truss: 107.5 + 562.0 + 107.5 m Cable: 147.5 + 570.0 + 147.0 m

Tower works Structural type:

Longitudinal direction: flexible hinge at top of tower Transverse: 3-story frame rigid (1 story above road)

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Tower height: Height of tower foundation: Centre distance between towers:

121.866 m (cable theoretical top: 126.0 m) P36 (Shibaura Main Tower): 2.866 m P37 (Daiba Main Tower): 4.5 m P36 (Shibaura Main Tower) at foundation: 30.862 m at tower top: 30.084 m P37 (Daiba Main Tower) at foundation: 30.851 m at tower top: 30.084 m

Cable works Cable type: Structure dimensions: Cable diameters: Strand: Wire: Hanger rope:

PWS (parallel wire strand) Main span sag: /= 57.6 m; sag ratio: n = 1/9.9 Centre distance between cables: 29.0 m Main span: 762 mm; 127 strands per cable Side span: 771 mm; 130 strands per cable Diagonal; 69.8 mm 0 5.37 mm 0; tensile strength: 160-180 kg/mm2

Centre Fit Rope Core (CFRC); 4 ropes/panel point

Stiffening girder works Structural type: Hanging type: Structure dimensions: Upper floor system: Lower floor system:

Main structure: parallel chord Warren truss Lateral bracing: K-truss Anchoring to upper chord Main structure height: 8.9 m Main structure width: width: 29.0 m Expressway (multi-span continuous steel deck girder, effective width: 9.25 m) Note: Main span is of 56 span continuous structure, rigidly connected at both ends Port roadway (multi-span continuous steel deck girder, effective width: 7.5 m, including walkway 1.5-2.5 m wide) Rail transportation system (multi-span continuous steel deck girder, RC track gauge: 1.7 m)

Table 3: Basic structural specifications

The concrete volume of each anchor-age, including the top slab of the cais-son, amounted to 60000 m3. In order to reduce cracking caused by the heat of hydration, an ultra-low-heat cement was used. In addition, liquid nitrogen was sprayed onto the aggregate, result-ing in temperatures of about 3°C for

the sand and -27 to 15 °C for the grav-el. Finally, preset water pipes further helped to cool the mix after placement. Superstructure The steel weights for the superstruc-ture included 14100 t for the towers;

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83001 for the cables, 23 7001 for the stiffening girders. The basic specifica-tions for the tower, cable and stiffening girder works are shown in Table 3.

Fig. 32 The main towers (Fig. 32) are made of hollow steel box section and were each assembled in three large blocks using 33001 and 41001 (hanging weight) floating cranes. Until erection of the main cables, free-standing towers of suspension bridges experience vibra-

tion due to wind forces. Based on wind tunnel tests, damping devices in-cluding an active mass damper, were installed at the tower tops to resist pos-sible vortex-excited vibration. A main cable consists of 130 strands (each composed of 127 wires) in the side spans and 127 strands in the cen-tre span. Since the short side spans of the Rainbow Bridge might have en-countered a problem due to unbalanced tensile forces in the main cables on each side of two towers, three addi-tional cable strands were installed in the side spans to balance the stress level in the main cable. In addition, a "horizontal frictional board" with an increased surface friction coefficient was fitted to the towers' top cable sad-dles to further resist cable slippage due to any unbalanced tension. After erec-tion of the strands, the cable was shaped using a squeezing machine. The Rainbow Bridge also features a multi-continuous (56-span continuous) steel deck floor system with improved shoes on its upper deck. There are no expansion joints in the centre span of the expressway, resulting in a comfort-able driving surface and reduced main-tenance requirements. Aesthetics From the outset, the owner was very conscious of the environmental and vi-sual impact of the bridge, given its prominent location in the Port of To-kyo. A Committee on Aesthetics was established and much attention was paid to architectural and structural de-

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tails throughout the design and plan-ning of the crossing. The rounded corners and reduced bolt connections of the main towers' col-umns and beams, as well as the con-figuration and surface finish of the an-chorages, resulted from aesthetic con-siderations. The graceful configuration of the bridge is illuminated at night by white, green and coral pink lighting. The lighting pattern varies with the seasons and times of day. For its illu-

mination design, the Rainbow Bridge was awarded the Paul Waterbury Award of Distinction for Outdoor Lighting by the Illumination Engineer-ing Society of North America. Owner/Engineers: Metropolitan Ex-pressway Public Corp. (MEPC), Tokyo Construction duration: 6.5 years Service Date: August, 1993

THE TÄHTINIEMI BRIDGE, FINLAND Esko Jarvenpaa, Technical Dir. Pekka Pulkkinen, Civil Eng. Suunnitte-lukortes AEK Ltd, Oulu, Finland Reiner Saul, Managing Dir. Leonhardt, Andra and Partner, Stutt-gart, Germany Introduction In 1988 the Finnish Roads Administra-tion organised a design competition for a technically advanced bridge which would adapt well to the lake landscape near the city of Heinola. Heinola is one of the most beautiful cities in Finland, about 130 km north of Helsinki on the route to a lake area where many vaca-tion cottages are located. The winner of the competition, now known as the "Star of Heinola", is a single-pylon cable-stayed bridge (Figs. 33, 34). It is the largest bridge in Fin-land, with a total length of 924 m. The

main span is 165 m and the width of the deck varies from 22 to 30 m.

Fig. 33 Design Competition The competition was limited to four Finnish bridge engineering companies. The design brief was very demanding. Among the most important parameters were the site, the difficult foundation conditions, the curvature of the road-way and the need to maintain free-flowing marine traffic, including a busy logging channel. Maximum water depth at the site is 24 m, and the bridge is situated in a natural lake landscape, near the town. Ten proposals were delivered to the competition jury. Five were traditional composite girder designs; one was a

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single pylon design and three were double-pylon cable-stayed designs. There was also one truss bridge pro-posal. In the superstructures of the composite girder bridges, reinforced compression slabs were used in the areas of the in-termediate supports, and longitudinal prestressing in the deck slab. Due to the considerable width of the deck that was required, there were inclined steel

struts in the cross sections of two steel girder designs for this type. The cross section alternatives for the cable-stayed bridge designs were a concrete box girder, a composite gird-er, a composite box girder and a com-posite slab beam which was pre-stressed in two directions. The foundation solutions were very similar in all bridges. In deep water, composite steel pipe piles were used.

Fig. 34 Other supports were founded on soil or rock. The diameter of the piles varied from 700 to 1500 mm. The winning design, with its single 105 m high pylon, serves as a dramatic gateway to the lake district of Finland. Its cable-stayed spans are placed over the open lake so that the heavy marine traffic can operate with minimal ob-struction.

Bridge Design The client wanted to assure adequate traffic-handling capacity of the bridge far into the future as well as under ex-ceptional circumstances. Thus, it was decided that the bridge should be de-signed for far heavier traffic loads than current Finnish load codes specify.

Deviating from Finnish load specifica-tions, the full traffic load can be car-ried on one side of the bridge deck when there is simultaneously a special heavy truck on the other. If the cables have to be changed in the future, only one edge lane has to be closed. Also, the pylon was designed for greater wind loads than specified in the exist-ing code. Crash loads of ships have been taken into consideration in the design of the intermediate support. The five middle supports are founded on composite steel pipe piles; other supports are founded on soil or rock. The steel piles were designed as a composite structure with a 4 mm thick-ness of the steel pipe wall allowed for corrosion. The diameter of a pile is 813 mm and thickness is 16 mm. Rein-

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forcing bars are placed in the upper-section of the piles. The cross section of the deck is a tradi-tional composite structure of two open girders. The girders are 3.2 m high I-beams (Fig. 33). There are crossbeams at 7 m centres. On the crossbeams there is a 1 m high secondary longitu-dinal girder. In the north part of the bridge, where the deck is 30 A wide, there are two secondary girders. The cable crossbeams are inclined to the cable direction. Between the main girders, the cross section of the cable crossbeam is an open I-beam. The girders are stiffened with steel bars. Outside the main girders, the cable crossbeam is a composite box girder. In the competition proposal, the pylon was a steel structure. In the general de-sign, the costs of steel, composite and concrete pylon were compared. The concrete pylon proved to be the most economical. The pylon is formed of two T-shaped hollow concrete towers which are joined together by two crossbeams. There is an elevator inside one tower and stairs inside the other. The hori-zontal geometry of the road has a cur-vature of R = 4000 m. This caused large horizontal forces on the towers. Therefore, the pylon was not placed centrally to the deck cross section, but with an eccentricity of 0.6 m. Due to this placement, the horizontal forces, and hence, the number of steel piles decreased considerably. The bridge has 24 factory-fabricated parallel wire cables. The cables consist of 7 mm steel wires (253-403/cable) injected with grease inside a high den-

sity polyethylene pipe that is covered with white Tedlar tape. The pylon and cables are illuminated at night. The fixed bearing of the bridge is at the southern abutment. It is a hinged structure, where horizontal forces are transferred large steel bars. Construction The piling and the concreting of the foundation slabs and columns took 14 months. The joint welding of the steel girder sections and the launching were completed in one year. The largest concrete works, such as towers and deck slabs, were placed in summer, because the temperature in winter can be as low as -25 °C. At the beginning of the construction period, the design for the pile founda-tion was changed to a caisson struc-ture. The caissons were built in a dammed trough on the north side of the bridge. The caissons were floated into position and the piling work was done through access holes in the cais-son slab. Finally, the piles and the in-ner part of the caisson were cast in dry conditions. Except for the slab of sup-ports T3 and T9, all casting work on the substructure was done in dry con-ditions. The casting of pile slabs suc-ceeded well and there were no faults typical of underwater concrete casting. The steel girders of the superstructure were launched from both abutments and joined by welding between sup-ports T5 and T6. Three auxiliary piers had to be built for the cable:stayed spans during launching. The top of the girder was lifted on a pontoon when

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the spans exceeded 70 m. The launch-ing bearings were vertically adjustable because the girder was very stiff. The longest beam sections were 42 m long and the maximum weight was almost 80 t. The bridge was originally designed us-ing steel grade Fe 355 E, but the steel contractor and steel manufacturer pro-posed to change the steel grade of the support sections of the girder to a new thermomechanically manufactured S 420 ML steel. Using this material, the contractor slightly reduced the weight of the girder and benefited from the superior welding properties of the new steel grade. The total amount of steel in the superstructure is about 50501. The towers of the pylon were cast us-ing a climbing formwork, with the height of one casting section being 4.15 m. The longitudinal reinforcing bars were jointed with screw sleeves. The crossbeams between the towers and the cable anchor areas were pre: stressed. The surface of the concrete tower had to meet stringent quality re-quirements. A textile covering was

placed on the formwork surface to en-hance the strength of the concrete sur-face and to reduce air blisters. A green concrete paint was applied to the sur-face of the pylon. Construction of the pylon was compli-cated because it has three inclined walls. Therefore, the scaffolding had to be adjusted at every stage. The rein-forcing of the cable anchor area was difficult because of restricted space. The temporary support structure of the

upper crossbeam was also difficult to install and there were problems to sta-bilise it. Nevertheless, the pylon was completed on schedule and all casting work was completed before winter. The deck slab of the superstructure was cast using two movable scaffold-ing units. The longest casting section was 24 m. The slab was prestressed transversely in two equal stages. The stay cables were installed from the bottom upwards. Cable stressing was accomplished using four jacks at the level of the deck slab. The cables were stressed in pairs. The total weight of stay cables is 214 t. They were tested against fatigue and ultimate load, the test cable being the largest cable of the bridge. In the fatigue test, where a 5 m long test Cable was loaded 2 million times with a stress variation of 193 MPa, only 9 wires broke. After this test the same cable was stressed up to the breaking load, 24.6 MN. Client: Mikkeli Road District

Design: Suunnittelukortes AEK Ltd, with Leonhardt, Andra and Partner Main contractor: WT Corporation Ltd Steel contractor: PPTH Steel Ltd Construction duration: January 1991 to November 1993

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THE PITAN BRIDGE, TAIWAN Kwong M. Cheng Pres., OPAC Consulting Engineers, San Francisco, CA, USA Introduction To alleviate traffic congestion near Taipei, in 1985 the Taiwan Area Na-tional Freeway Bureau planned the construction of the 108 km long North-ern Taiwan Second Freeway. The ma-jority of the Second Freeway's align-ments are on grade, on embankments, in tunnels, or on viaduct structures. At several locations, however, obstacles were identified that required special bridges. The Pitan Bridge spans one of these areas. The Pitan Bridge, actually two nearly parallel bridge structures, is located about 15 km south of Taipei. It con-nects typical low-level viaducts to a tunnel. Both bridge units have a total length of approximately 800 m, a 750 m radius curvature and a slope of ap-proximately 1%. The Pitan Bridge has become a landmark in this suburban area of Taipei. Selection of the Bridge Type The design of the Pitan Bridge was based primarily on the 1983 AASHTO Standard Specification for Highway Bridges, the 1987 AASHTO Design -and Construction Specifications for Segmental Bridges (No. 2 Draft), and local design codes. Among the general constraints and concerns that guided the design of the bridge, it had to:

- meet all freeway design and perfor-mance requirements of the Northern Taiwan Second Freeway - be aesthetically pleasing, construc-table, and economical - require minimum maintenance. The following factors were considered in the selection of the bridge type: - Structural systems issues such as bridge piers, span lengths and ar-rangement, foundations, vertical and horizontal clearances, capacity to resist horizontal forces and seismic actions, etc. - Aesthetic issues such as the overall appearance of the bridge, its com-patibility with the surrounding land-scape and with existing built facilities - Construction issues such as the con-struction method, equipment, con-struction time and the capabilities of local contractors - Cost issues such as the cost of relat-ed works, of maintenance and the cost of the bridge itself. Four bridge types consisting of varia-tions on girder-and-arch designs were identified as potentially meeting the above design considerations. The selected bridge type consists of a post-tensioned cast-in-place concrete box girder bridge deck supported on delta-shaped reinforced concrete box piers, which are joined together at the centre of the main span to form an arch. This scheme adapts well to the constraints of the site and provides a stiff, strong bridge with a clean, effi-cient, and very modern appearance.

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Basic Layout The two almost parallel bridge struc-tures have nearly identical structural layouts. They each consist of nine

spans totalling 781.5 m, with a 160 m main span. The northbound bridge has an additional simple span of 21.7 m (Fig. 35).

Fig. 35 Expansion joints have been kept to a minimum, located only at the extreme ends of the structure. The four main bridge piers (3, 4, 5 and 6) are fixed to the girder and footings with monolith-ic, moment-resisting connections. The smaller piers and the abutment are fixed to their footings only and support the girder through bearings that are fixed transversely, having some lim-ited freedom-to slide longitudinally. This combination of few expansion joints and high pier fixity was evaluat-ed for serviceability under the required seismic excitation, as well under the influence of creep and shrinkage in the concrete, and temperature change in the structure. The piers and founda-tions provide enough flexibility so that the time-dependent strains and tem-perature strains of the concrete, accu-mulated over the entire girder length between expansion joints, cause ac-ceptably small bending stresses in the piers and axial stresses in the girder. The preliminary design made use of simple and rational analytical tools that have proven reliable for many struc-tures. The following were considered at this stage of the design in order to

determine the dimensions of the main structural elements of the bridge: the cross section, the longitudinal system, the pier shafts, footings and piles. Superstructure Design Detailed design and analysis made use of more refined analytical tools in or-der to verify the preliminary design. The following tasks were performed: - development of structural models for service-load analysis - evaluation of design values for mo-ment and shear - transverse and three-dimensional considerations - pier moments, shears, and axial forces - thermal effects. The bridge superstructure consists of a single cell box girder (Fig. 36). The di-mensions of the box girder were de-signed to comply with the strength re-quirement as well as provide space to house the necessary prestressing ducts. The main span girder depth varies from 8.882 m at the face of the delta-shaped pier to 3.5 m at mid-span, and is prestressed longitudinally with can-

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tilever tendons in the top slab and con-tinuity tendons in the webs. All pre-stressing is grouted in ducts embedded in the slabs and webs of the girder.

Fig. 36

The top deck longitudinal prestressing is dimensioned to resist all structural dead loads during cantilevering, as well as construction loads and the weight of the travelling formwork. All anchorages are located in the well-confined and reinforced intersection fillets at the tops of the webs. The web longitudinal prestressing is dimensioned to provide adequate mo-ment capacity and stress control at

mid-span and over the pier to resist su-perimposed dead load, live load, creep, and temperature moments. Each of these tendons extends over the full length of a span, and is anchored in the diaphragm walls over the pier. The deck transverse prestressing is di-mensioned to resist transverse bending from dead load and live load. The gird-er cross-section reinforcement includes a grid of mild steel bars in each direc-tion on each face of each structural el-ement. The delta-shaped piers are designed to reduce the length of the main span, thus allowing the relatively slender box girder to meet the strength and stiffness demands on this bridge. They are designed as wall-type elements with post-tensioning to provide a re-sidual compressive stress under com-bined axial force and bending for all service load conditions. The schematic prestressing layout of the main span is shown in Fig. 37. Seismic Analysis and Design

Fig. 37

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Initial, seismic analyses were per-formed in accordance with the local seismic design criteria. These analyses provided controlling conditions for de-sign of the piers and foundations. A more refined analysis using earth-quake response spectrum developed for the vicinity of the site, was used later to verify structural dimensions and reinforcement requirements. Substructure Design Each pier consists of a four-walled cel-lular reinforced concrete shaft, heavily reinforced to form a ductile cellular el-ement. All fixed piers participate in providing the required capacity to re-sist seismic and horizontal forces. For transverse seismic loads, the piers be-have as cantilevers, with significant moments developed at the bottom only. For resisting longitudinal seismic excitation, the main piers behave as members in a rigid frame. The creep, shrinkage, and temperature deforma-tions of the superstructure are ade-quately accommodated in the mono-lithic piers by the flexibility of the foundations and the pier shafts. The basic cross section of the main piers continues through the depth of the box girder cross section to provide diaphragms capable of developing the plastic moment of the pier into the girder. These diaphragms also provide a convenient location for anchorage of the longitudinal prestressing tendons in the superstructure. The abutment is designed as a conven-tional cantilever wall which supports the bridge girder on sliding bearings. The footing blocks supporting the piers

were designed for the static dead and live impact loads and the seismic loads such that the movements at the base of the piers are within allowable limits and no plastic hinges develop below the ground surface. Foundations consist of 2.0 m diameter drilled, cast-in-place, reinforced con-crete piles, supporting reinforced con-crete footing blocks. The piles, up to 14 m in length, act as friction piles with some limited end-bearing support. Analysis and Modelling Constructability will largely determine the success of a project. Therefore, a thirty-eight step stage-by-stage analy-sis of the bridge was performed to vali-date the time-dependent behaviour of the construction sequence. The analy-sis included: - development of structural computer models for construction procedure - evaluation of stresses and deflections at critical construction stages - evaluation of stresses and deflections over the service life of the bridge. The bridge was modelled using a com-mercially available general-purpose structural analysis program which is capable of static and dynamic analysis of finite element models for a wide range of structure types. All important structural features of the bridge were modelled, including the piers, the box girder, and the delta-shaped piers. The girder was modelled as a line of frame elements represent-ing the entire cross section, oriented along the centroidal axis of the proto-type girder. The piers were modelled

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similarly, including semi-rigid ele-ments in the pier-girder intersection. The intersection zone between the delta-shaped piers and the girder was modelled by a separate finite element

model in order to capture the stress distribution between the diaphragms and the webs in this area.

ROOSEVELT LAKE BRIDGE, GILA COUNTY, ARIZONA Maurice D. Miller, Civil Eng. HTNB Corp., Kansas City, MO Crossing Roosevelt Lake Located in Gila County, a rugged area of east-central Arizona, Roosevelt Lake is a hydroelectric reservoir used for flood control, irrigation and recre-ation. It is midway between the cities of Globe, which is the county seat, and Payson, in a ranching and recreational area. State Highways 88 and 188 con-nect the two major cities. From Globe, Route 88 winds northwest through de-sert canyons and along the south-west shore of Roosevelt Lake to a masonry dam, where it connects with Route 188 and continues west and north to Pay-son. The one-lane road traversing the dam across Roosevelt Lake had not been improved since construction of the -dam in 1911. Travel across the dam was slow and treacherous, with abrupt 90° blind corners. When two cars met on the dam, one had to yield the right-of-way and back up, a gesture that was not always made willingly by the local ranchers. Because of the narrow and crooked route over the dam, vehicles over 9 m in length were prohibited. Commercial traffic between Globe and Payson was forced to detour through Phoenix, add-

ing hundreds of miles to the route. Al-though traffic congestion was im-portant, the deciding factor for the new Roosevelt Lake Bridge was flood pro-tection. When the US Bureau of Rec-lamation raised the dam by 23.5 m to provide additional protection to Phoe-nix and the Valley of the Sun, it re-moved State Highway 188 from the dam. Bridge Type Selection Located about 305 m upstream of the dam, the new Roosevelt Lake Bridge is just below the confluence of the Salt River and Tonto Creek. Here, the Salt River just begins the erosion of its canyon through the Mazatzal Moun-tains. The steep-walled features of the canyon were ideal for the construction of the world's highest masonry dam, creating a lake 300 m wide and 60 m deep at the proposed crossing. The Arizona Department of Trans-portation based its selection of the best type of bridge for the crossing on eco-nomics. Because of the steep valley walls and the deep valley floor, under-water foundations were determined to be too costly. The two-lane bridge would have to span the lake with foot-ings on each shore. Two engineering firms prepared complete construction plans for two alternatives: a steel box-

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rib-through-arch and a concrete stayed girder bridge. The box-rib-through-arch was selected for the steel alternative based on an in-depth study of three steel bridge types: trussed-through-arch, box-rib-through-arch, and cable-stayed girder. The twisting alignment required for the mountainous terrain made it difficult to get a tangent alignment long enough to accommodate minimum-length back spans for the cable-stayed and trussed arch bridges. The arch span was the most economi-cal. It adapted readily to the curved alignment of the approach structures and had superior aerodynamic proper-ties. The welded steel arch was the overwhelming favorite of most bid-ders. It was bid at 30% less than the concrete alternative. Arch Rib Design Existing terrain and future lake levels were important factors in establishing the arch rib geometry. The arch spring-line is at Elevation 649.5 m, well be-low the 200-year flood elevation of 663 m. To keep the steel arch above water, the lower 158 m of the arch rib is made of concrete. The resulting composite steel-concrete structure con-sists of the following sections: 21.6 m of concrete rib, 323 m of steel rib, and 21.6 m of concrete rib, for a total arch rib length of 366.4 m and an arch span of 329 m. The steel and concrete portions were made continuous by anchoring a base plate at each of the steel-concrete con-

nections. This required 32 MN of pre-stress force at each base plate. The geometry of the entire arch rib op-timizes the use of material through the length of the rib. The depth of the steel box section varies from 2.44 m at the crown, where compressive forces are the smallest, to 4.27 m at the base, where compressive forces are the greatest. The shape of the arch rib was also established to minimize the dead load bending stress in the arch. The re-sultant shape is defined by both second order and fourth order curves, making the entire arch appear smooth and con-tinuous. The steel arch rib section is made up of two 1.2 m-wide flanges with two web plates that vary from 2.44 m at the crown to 4.27 m at the base plate. The webs of the box section are stiffened by two T-sections welded to each web. The stiffeners are continuous and par-ticipate fully in carrying the various loads. Sixteen longitudinal fillet welds, over 13.4 m long, were required to connect the flanges and the stiffeners to the webs. Stability against global buckling and transmission of wind loads for the arch rib, which is 15.2 m center-to-center, was achieved through the use of a K-bracing system fabricated from struc-tural tubing and welded box sections. The selection of the K-bracing was based on both first-cost and life cycle costs. The K-bracing required 901 less steel and reduced wind deflections to half as much as those caused by a comparable Vierendeel system. The closed tubular sections were selected to minimized corrosion due to entrap-

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ment of water and debris. To totally close the ends of the tubular shapes, horseshoe-shaped plates were welded to the ends of the tubes. At the portals, the K-bracing was ter-minated with a three-dimensional X-shaped connection. The multi-jointed, three-dimensional intersection of the bracing was achieved by welding plates into an octagon and welding the ends of the tubes to the sides of the oc-tagon. More than 760 m of fillet welds were used to make up the bracing. Another part of the bracing system is a 2.1 m square welded box strut between arch ribs directly below the roadway at each end of the bridge. Access to the interior of the ribs is through lockable doors in these boxes. Electrical distrib-ution centers are also inside the struts. The floor system for the 11.5 m wide roadway consists of longitudinal stringers, supported on welded I-girder floor beams. Floor beams are spaced at 15.2 m centers and are hung from the arch ribs with eight wire ropes, four at each end of a floor beam. Welded steel girders 2.0 m deep are used as exterior stringers and also function as stiffening girders for aerodynamic ''stability. About 2.1 m of fillet welds were re-quired to fabricate the floor system. The overall stiffness of the system -

arch ribs, bracing, and floor - was veri-fied by wind tunnel tests. Erection Erection of the bridge was accom-plished using temporary towers resting on the arch footings and a system of bridge strand backstays and forestays. Hydraulic jacks in the stays allowed alignment adjustments to be made dur-ing erection. The erection progressed by lifting and bolting successive 15.2 m long welded steel rib sections into place with a barge-mounted crane floating on the lake. As adjacent rib sections were placed, the welded tubular K-bracing was installed to maintain alignment and rigidity of the ribs. Shop fabrica-tion accuracy was maintained so well that there were no mismatches during erection. Owner: Arizona Dept of Transportation Engineers: HNTB Corp., Kansas City, MO Main contractor: Edward Kraemer & Sons, Inc., Plain, WI Service date: 1990

BRIDGE SCOUR FAILURES D.V. Mallick M.M.Tawil Technical Advisors National Consulting Bureau, Tripoli, Libya

Introduction Failure of a bridge is viewed seriously by the public since it involves not only traffic disruption and the loss of tax payer's money but can also result in

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loss of human lives. It reflects on the reliability of the design procedures as well as on the quality of construction. Use of poor construction materials and inadequate design assumptions are generally this suspects. Designers and contractors have to be extra cautious while designing and constructing bridges to resist the effects of natural hazards like floods, earthquakes and landslides in addition to normal traffic loads. Studies have been made in re-cent years to understand the pattern of occurrence, of these natural phenome-na statistically, attempting to compute probability of their future occurrence. The cumulative effect of various as-sumptions and approximations intro-duced at the analysis and design stage of a bridge which are not sufficiently

covered by load or safety factors are revealed in weaknesses after construc-tion. Geotechnical investigations are very important for the design of bridge foundations. This paper describes a case history of failure of three reinforced concrete (RC) highway bridges built across Wadi El Nagah watercourse in the northeastern part of Libya. Two out of three bridges collapsed and one suf-fered damage that could be repaired. All these bridges have been victim of heavy floods in the wadi, which caused severe damage due to scour, erosion and undermining of the soil below the foundations of intermediate piers and the abutments. In all cases, parts of the approach road embankments were also washed away.

Fig. 38

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Description of the Bridges The location of three bridges built across Wadi El Nagah are shown in Fig. 38. The catchment area of the wadi across which these bridges were built consists of hilly terrain. Mean an-nual rainfall precipitation in this region is around 400-600 mm. Almost all the precipitation occurs during the winter months, from October to January of each year. Bridge A, built about three decades ago, consisted of three simply sup-ported spans of pre-stressed reinforced concrete beams supported on two cen-tral piers and two end RC abutments. The foundation of all these supporting elements consisted of shallow block foundations. Bridge B was a bowstring girder RC bridge supported on two massive intermediate plain concrete pillars and anchored at both ends to earth fill embankments. Bridge C, part of the new coastal highway, consisted of an RC portal frame with propped overhangs. Vertical supporting mem-bers of the portal are shear wall type piers 10 m high and 0.7 m X 6.0 m in cross section. The foundations of these piers consisted of RC blocks 10 mX 5 mX 1.5 m resting on plain concrete mats of 300 mm depth and located 4 m below the planned wadi bed level. The RC abutments of this bridge were em-bedded in the approach road embank-ments at both ends. Gabion protection was provided as per the design. Damage Assessment Bridge A was badly damaged by the flood water. One abutment collapsed

and the beams at that end of the span were twisted. Foundation blocks of the intermediate piers were exposed. Part of foundation soil of the far end abut-ment eroded away, leaving the founda-tion block partially suspended. Expan-sion joints between the concrete deck sections over the intermediate supports widened considerably due to distortion and the lateral displacement of the bridge decks. The old multispan RC bowstring girder Bridge B totally collapsed. Its two in-termediate plain concrete supporting piers overturned sideways along with the foundation blocks and moved downstream to Bridge C. The new Bridge C did not suffer any appreciable structural damage although scouring of the wadi bed, accompanied by undermining of the soil below the foundation blocks of the vertical piers and the east RC abutment did occur, leaving them partially suspended (Fig. 3). The approach connection to the bridge deck from the east was de-stroyed due to the collapse of the ap-proach concrete slab caused by erosion of the earth fill at the back of the abutment. This bridge has been re-paired and opened to traffic. Causes of Damage Scour of the wadi bed, undermining the soil below the intermediate piers and the abutments' foundation blocks, and the erosion of the approach road embankments during a heavy flood, were the causes of the damage and col-lapse of these bridges. This is not the first time such damage has occurred.

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"Bridges are vulnerable to natural haz-ards ranging from hurricanes to earth-quakes. But scour is the problem that has caused more bridges to Mil than all of rest combined. One study... con-cluded that among 86 bridge failures [in the USA] from 1961 to 1976, 48 were due to floods. Out of 48, 46 were due to bridge scour" [1]. Another re-cent survey revealed 494 of the 823 bridge failures in the USA from 1951 to 1988 were primarily the result of scour of foundation material [2]. In addition, some other circumstances aggravated the damage and led to col-lapse of one of these bridges. The dam-ages occurred partly due to shortcom-ings of the design and partly due to ig-norance of the effects of a temporary road embankment across the wadi about 500 m upstream from Bridge A [3]. This temporary road embankment acted like an earthfill dam across the wadi, creating an artificial lake up-stream. Due to heavy floods, this dam' gave way, releasing a flood with a fast moving flow of water about 12 m high, as observed from the water marks on the soffit of the deck of Bridge C, re-sulting in erosion and undermining scour of the wadi bed and the side em-bankments. The damage to Bridge A was severe due to its undesirable loca-tion at a bend in the wadi, as shown in Fig. 38. Rehabilitation Two of the three bridges on Wadi Al Nagah were abandoned and the third, Bridge C, has been rehabilitated. The main problems in rehabilitating Bridge

C were to support the foundation blocks of one intermediate pier and one abutment, and to provide a new reinforced concrete approach road slab. The repair work had to be planned very carefully in order not to disturb the structural safety of the other parts. of the bridge. The sequence of the re-pair work consisted of removing loose and eroded soil from below one side of the foundation block at a time, thor-ough compaction of the base and measuring any deflection of the sus-pended part of the foundation block. This part was then block concreted. Similarly, the other side of the pier was prepared and block concreted. To ensure proper contact between old and the new concrete blocks, epoxy mortar was injected between them. Then the central part below the foun-dation block was cleared of all soil de-posits. Precast concrete beams were in-serted on the prepared base. Finally, the end sections were grouted, thus providing another foundation slab to the existing foundation block. A simi-lar procedure was adopted for the re-pair of the abutment foundation. The depth of the new foundation system was based on scour depth calculations. After carrying out all necessary repairs for rehabilitation, the wadi bed and ap-proach road embankment slopes were suitably protected. This bridge has now been operational for two years. The owner was advised to dismantle Bridge A, so as to provide a clear path for the wadi stream approaching Bridge C. To date, this damaged bridge has not been removed.

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Lessons - Bridge planning and design is not only a job of structural engineer, but is the joint responsibility of a team of structural, hydrology and geotechnical engineers. Structurally well designed bridges have failed as a result of hy-draulic conditions, primarily due to scour of foundation material. - The uncertainty of collecting proper hydrological data, the probability of occurrence of future severe storms and their effect on the bridge system re-quire advance preparation for all eventualities. - Initial evaluation of scour vulnera-bility of streambed material is es-sential. Due to the stochastic nature of the hydraulic parameters involved in bridge design, appropriate scour countermeasure programmes, like in-stalling riprap, guide banks to protect abutments and embankments and sheet piling along the face of piers and/or abutments, must be clearly planned in advance.

- Location of a bridge near a bend in a stream should be avoided. - There is a need for research to es-tablish the relationship between flow depth, flow velocity and total scour depth for actual conditions in the field. References [1] MURILLO, J. A. The Scourge of Scour. ASCE Civil Engineering, July 1987, pp. 66-69. [2] HUBER, F. Update: Bridge Scour. ASCE Civil Engineering, September 1991, pp 62-63. [3] MALLICK,D.V.; ELWAFATHI, A.M. Damage Study of Three Reinforced Concrete Bridges over Wadi El Nagah, Libya. Conference on Our World in Concrete & Structures, Vol. VI (1987), Singapore, 25-26 August 1987, pp 50-66.

A NEW FOOTBRIDGE, AUSTRIA Harald Egger, Prof. Dr Hermann Beck, Research As-sist. Univ. of Technology Graz, Graz, Aus-tria Design At the site selected for a new foot-bridge, the banks of the Mur River in

Graz. Austria, have an elevation dif-ference of about 2.2 m. The designers felt that a simple straight beam in-clined across the river at this point would be aesthetically unsatisfactory. They therefore opted for spanning the river with a beam that was slightly ele-vated at its centre and horizontally supported by columns, with its upper surface serving as a footpath.

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footpath divides "before leading down to the left and right. The aim of design-ing a fine-membered bearing structure led to the development of a compound beam construction comprising a stiff-ening member, with a tensioning mem-ber and a compression member on the underside of the bridge (Fig. 39). The height and width of the stiffening member decrease toward the centre of the bridge from the supports at either end, i.e., toward the compression member. The shape of the composite prismatoid thus also determined the spread of the tensioning member un-derneath toward its supports. In accordance with the geometry and design principle of the entire construc-tion, the bridge deck has been designed as a folded plate structure forming an integral part of the bearing system. On one bank the deck rests upon the body of the, stiffening member; on the other bank it extends from the stiffening member's sides.

The bearing structure of the bridge rests on two pairs of columns on the banks of the river, cantilevering on ei-ther side. On the right bank it extends to the old non-bearing embankment wall, while on the left-hand bank the body of the stiffening member ends in a cantilever design, with the walking deck extended from it to permit direct access to the footpath without ramps or stairs. Construction The stiffening member of the bridge covers an effective span of 55.8 m. Its cross section has a height of 2.0 m over the columns and 0.7 m at the Cen-tre. The bridge deck, a hollow steel plate, is folded on its lower side and forms part of the stiffening member. The deck is connected asymmetrically to the trilateral body of the stiffening member in relation to the centre of the bridge. On the left side of the bridge its

Fig. 39

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top follows the top edge of the stiffen-ing member; on the right side, starting from the centre of the bridge, it inter-sects with the lateral surfaces of the prismatoid, parallel to its bottom edges. The compound stiffening mem-ber is also asymmetrical. Its character-istic cross section is shown in Fig. 40.

Fig. 40

The walls of the trilateral prismatoid are 15 mm thick over its entire length, but its longitudinal braces - an addi-tional flange plate welded where the bridge deck begins to descend - were adapted to the asymmetry of the stiff-ening member, as was the quality of the plate used. The trilateral prismatoid is reinforced by transverse bulkheads placed 2.2 m from each other, corre-sponding to the folds of the cover plate of die bridge deck. The entire structure is sealed airtight. All parts, whether as-sembled in the shop and at the site, were joined by welding. In order to make sufficient allowance for floodwaters, the tensioning mem-ber underneath the bridge has a very flat design, with the elements spread-ing out from the centre to the supports, where they are eccentrically connected

to the stiffening member. This spread-ing is a consequence of the geometrical configuration of the bearing structure and design considerations. Stability of the stiffening member is also improved by this expansion and by the eccentric connections, the latter also reducing deflection of the stiffening member. To achieve the required stiffness for the entire compound bearing structure, 145 mm thick bands of grade Fe 510 steel were used for the tensioning member. These relatively heavy bands were attached to the stiffening member at the quarter points of the central bridge span and supported against wind loads. The connection of the ten-sioning bands to the compression member shown in Fig. 41, which illus-trates both the solution originally re-quired by the invitation to tender and the final method employed by the con-tractor. Behind the supports, the bands were anchored to angle cleats that were laterally welded to the sleeve plates of the stiffening member. The steel bands were stretched in place, but not prestressed. The stiffening member rests on four slender free-standing columns. It is fixed to one column, and longitudinal-ly movable but transversally fixed to the other three so that all four columns may contribute to the transmission of wind loads. In addition, the entire bear-ing structure resting on the columns is protected against transverse wind at-tack from below. For reasons of time and cost, the bear-ing structure of the bridge, which put heavy demands on manufacturing skills, was produced at the plant. It was

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manufactured in large sections which were then transported by road to the site, in part with the bridge deck al-ready attached to the bearing structure.

Fig. 41

These sections were assembled into larger units, whenever possible directly

on the river's banks, and hoisted into position by an automobile crane. Erec-tion was accomplished in three night-shifts. The sections were placed on a temporary support and the entire bear-ing structure was then joined together by welding. After a final insertion of the tensioning member on the under-side of the bridge, the auxiliary support was removed. Architects: G. Domenig and H. Eisenköck, Graz, assisted by G. Wallner Civil Engineers: H. Egger, Graz, assisted by H. Beck Contractors: Alpine Bau (concrete), Salzburg Vöest-Alpine (steel), Linz Service date: 1993

IS ISO 9001 EFFECTIVE FOR ENGINEERING CONSULTANCIES? Jørgen Laustsen, Civil Eng. Copenha-gen, Denmark The quality assurance processes de-scribed in ISO 9001 have not been greeted with unanimous enthusiasm by consulting engineers. Consultants in England, Germany and Denmark have in fact responded quite differently to the ISO 9001 quality assurance stan-dard. Danish engineers have generally declined to adopt the standard, the Germans are decidedly more keen on their own DIN standards, whereas the English have sought ISO certification

on a large scale - but mostly for the sake of marketing. Attitudes towards ISO 9001 among English, German and Danish consult-ing engineers were the subject of a re-cent research study [1]. The study is based on interviews with twenty-nine consulting engineering companies and institutions. Thirty-five additional companies responded to questionnaires on the subject. Criticism in Denmark In Denmark the Association of Con-sulting Engineers (FRI) has rejected

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the ISO standard, arguing that it does not cover all the critical elements of a knowledge-based service. As a conse-quence of this position, dialogue be-tween ISO and FRI has ceased. Only one consultancy had been certi-fied in accordance with ISO 9001. The majority of companies have instead es-tablished a quality assurance system based on the paragraphs in the standard that seemed relevant, supplementing them as required. Several companies have likewise produced cross refer-ences to the ISO standard, as some cli-ents have demanded a quality assur-ance system in accordance with the ISO standard. The standard is, there-fore, used - but always as a reference. Doubt in Germany In Germany, the ISO standard has only recently been introduced and until now only a few contractors have im-plemented it. As yet, no engineering consultancy has done so. Several con-sultants stated that they could not un-derstand the necessity of the ISO stan-dard. The general opinion of those questioned was that the way the Ger-man construction industry and the DIN standards are related makes the ISO standard superfluous. Activity in England The attitude towards the ISO standard (BS 7550) in England differs dramati-cally from the other two countries studied. Nearly 40 % of the companies in the survey had implemented ISO 9001 and were certified in accordance

with it. Additional companies had be-gun to implement the standard. This tendency is substantiated by a survey of the European Construction Institute (ECI), 52 % of whose members -contractors, consultants and clients -replied that they were certified, while 11 % were in the process of imple-menting the standard, and 16% ex-pressed the wish to do so.

Fig. 42

In conversations with English consul-tants it was not unusual to hear that they had/in fact, no expectations for substantial positive effects from imple-menting the standard. It is seen as a necessary evil, one which enables con-sulting engineers to qualify for projects where the client demands the ISO certificate. The standard and the quali-ty assurance system it promotes are thus seen as a dubious formality, use-ful only as a marketing tool. The real value of ISO certification seems limited. Both clients and consul-tants who were surveyed agreed that ISO 9001 certification does not actual-

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ly ensure better quality, but only that certain documented guidelines had been followed. In England, a small industry has grown up around the standard. Around 6000 persons now work on implementing, certifying and maintaining quality as-surance systems. No Extra Fee Is a client willing to pay extra for this extra initiative? A survey carried out by Prof. Peter Barrett, Salford Univer-sity, England, shows that only 3% of clients take quality assurance into ac-count when they select consultants. 95 % of the cornpanies and clients sur-veyed did not expect a higher price for the services of a certified company. Many employees still repudiate the quality assurance system, and many companies are still not working consci-entiously with the system. There is, for example, no widespread information about the costs of ISO-certified quali-fy. In all three countries, only the ex-penses of internal and external audits are registered. Only in Denmark are expenses such as compensation and reparations registered. In all three countries, however, there is no existing standard as an alternative to the ISO 9000 standard. Is ISO 9001 Applicable for Engi-neering Consultancies? Given the scepticism of so many of the respondents in the study, it is reason-able to question if the ISO standard is indeed applicable for engineering con-

sultancies. The standard was drawn up for manufacturing companies with tan-gible end-products. As the standard only covers the critical processes for that type of production, it is not certain that it is suitable for knowledge-based services like an engineering con-sultancy. The critical processes are not necessarily the same, so the question is: How relevant is the standard for consultancy. This can be illustrated in Fig. 42. The differences between product-based and knowledge-based endeavors are considerable. The main reason for this is the cognitive and iterative aspects of consultancy. The process is difficult to forecast and schematicise, which makes it problematic to assure quality. The process of the work of an engi-neering consultancy is illustrated in Fig. 43.

Fig. 43

Revision of ISO 9000 The complications stemming from the iterative work process has been con-sidered by the ISO/TC 176 Task Force when it started to revise the ISO 9000 standard. The standard has been split up into four main areas: - Hardware

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- Software - Processed materials - Service, including engineering con-sultancies. The structure of the standards ISO 9001, 9002, 9003 and 9004 is undergo-ing considerable change. ISO 9004 will, for instance, be used for contrac-tual situations in the future. When the revised standards are published at the end of 1996, the companies who have certified according to the existing standards have to re-certify within 12 months, a process that represents con-siderable effort and time. Too Late? Engineering organisations unfortu-nately have not been able to influence the coming revised ISO standards for service, but one initiative has been made through the establishment of a EFCA Task Force (European Federa-tion of Engineering Consultancies As-sociation). Regrettably, there are prob-lems with establishing the task force, and their work cannot be finished be-fore the revised ISO standard is prom-ulgated.

The ISO 9001 standard, in its revised form, will be a reasonable basis for an effective quality assurance system. The standard is a good starting point for a continuous quality optimisation, and thus a good basis for Total Quality Management (TQM), etc. Therefore, it is disappointing that no one has been able to support this initiative and in that way participate in the preparation of the standards and guidelines which will have considerable importance for engineering consultancy in the coming years. Reference [1] LAUSTSEN, J. Quality Assurance and the ISO 9001 Standard in Consult-ing Engineering Companies. M. Sc. research project at Loughborough Univ. of Technology, Dept of Civil Eng., Longborough, UK, September, 1994.

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-A-

abrasion истирание; стирание; износ; шлифовка, абразия abrasion hardness твердость на стирание abrasive wear износ (от стирания) abrupt slope крутой уклон absolute weight удельный вес absorb поглощать; всасывать; впитывать; абсорбировать absorber energy «гаситель» энергии (потока) absorption capacity поглощаемость absorptive power см. absorption capacity absorptive quality см. absorption capacity abstract абстрагировать; извлекать; перегонять; дистиллировать; абстрактный; отвлеченный abut примыкать; прилегать; граничить;

прикасаться; торец; пята свода; упор

abutment опора; упор; береговой устой (моста);

бык; контрфорс abutment bay береговой пролет abutment joint стык; соединение впритык abutment pier береговая опора (моста) abutment pressure опорное давление; давление на

устой abutment span береговой пролет (моста) abutment stone опорный камень; пятовый камень;

подферменник acceleration of gravity ускорение силы тяжести accelerator акселератор; ускоритель; вещест-

во, ускоряющее отвердевание бе-тона

access road подъездная дорога accident of the ground неровность местности; рельеф accident prevention предупреждение несчастных слу-

чаев; техника безопасности accomodation of traffic средства сообщения

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account valuation расходная смета accumulate накапливать; скоплять;

аккумулировать; нагромождать accumulated hydraulic power напор воды accumulation of mud заливание accumulation of snow снегозадержание; снеговой суг-

роб accumulative накопляемый; скопляемый; сбор-

ный acetylene ацетилен acid кислота; кислый; кислотный acid-producing materials кислотообразующие материалы acid-proof кислотоупорный acid residue кислотный остаток acid rock кислая горная порода acid soil грунт, дающий кислую реакцию acid treatment кислотная обработка alluvial soil наносной грунт aperture of a bridge отверстие моста approach cutting выемка на подходе к мосту; портальная выемка (тоннеля) approach span береговой пролет (моста) arch abutment устой (опора) арочного моста; пята арки arch bridge арочный мост arch span арочный пролет auger бур; бурав auger-hole буровая скважина auger-hole charge буровой заряд

-B-

backfilling засыпка грунтом back-pressure противодавление; реакция

(опоры) balance bridge подъемный мост balanced cantilever method монтаж пролетного строения ме-

тодом уравновешенной навесной сборки

balance level ватерпас; уровень bank окружать насыпью, валом;

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поднимать уровень; «банкет» (земл.) насыпь; вал; отмель; берег; дамба; поперечный уклон

виража; склон холма; крутой скат bank pier береговой устой; береговая опора bank protection укрепление берегов или насыпей barge derrick плавучий кран bascule bridge разводной мост bascule pier опора разводного моста bascule span разводной пролет моста base of slope проекция наклонной линии, заложение откоса base plate опорная плита bateau bridge понтонный мост; плавучий мост batter pile откосная свая; наклонная свая batter post свайная укосина; наклонная рас-

порка bay bridge мост через залив beach bridge см . bay bridge beam bridge балочный мост beam span балочное пролетное строение bearer supporting bracket опорная часть; опорная подушка bench mark реперная точка; репер; отметка

высоты над уровнем моря blow-out прорыв (насыпи) bluff work планировка откосов (естествен-

ных) boat bridge плавучий мост; понтонный мост bottom-road bridge мост с ездой понизу bowstring bridge мост с криволинейным верхним

поясом break water волнолом; волнорез; мол bridge строить, наводить мост; мост bridge abutment береговой устой моста bridge anchor анкерное закрепление опор моста bridge approach подход, подъезд к мосту bridge deck (decking) см. bridge floor bridge floor настил моста; мостовой настил; проезжая часть моста (констр.) bridge footing опора моста bridge framework пролетное строение моста

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bridge head укрепление (русла) перед мостом; предмостное укрепление bridge opening отверстие моста bridge seat береговой лежень; опорная часть

моста bridge site место будущего моста; место перехода (через реку) bridge survey изыскания мостовых переходов bridge with continuous beams неразрезной балочный мост bridge with trussed girders сквозной мост; ферменный мост bridging наводка моста; помост; настил bridging joist поперечная балка мостового на-

стила brook bridge мост через ручей bund набережная; дамба buried abutment обсыпной береговой устой моста buried dump насыпной грунт buried pier добавочная опора, поддержи-

вающая конец переходного про-лета (моста)

butment береговой устой моста; пята сво-да

butt соединять впритык; стык; комель; торец

butt joint стыковой шов butt junction соединение впритык buttress подпирать; подкреплять; бык; ус-

той, подпора; опора; контрфорс

-С- cable bent tower пилон висячего моста camber подъем (моста) canal bridge мост через канал cantilever консоль (моста); кронштейн; консольный cantilever span консольная часть пролетного

строения моста carry the traffic воспринимать действие проезда; выдерживать движение carrying capacity допускаемая нагрузка;

219

грузоподъемность; пропускная способность

carrying traffic допускаемая интенсивность движения; «работоспособность»

дороги caving bank оползающий берег centre line (of pavement, road, bridge) ось (дороги, моста) chain bridge цепной мост chain drag bridge цепной подъемный мост channel span пролет моста над наиболее дос-

тупной для судоходства частью реки

clear headway of the bridge подмостовой габарит; габарит проезжей части моста по высоте clearance просвет; зазор; промежуток; раз-

мер в свету; отверстие (моста) combination bridge мост смешанной конструкции combined bridge мост под обыкновенную и желез-

ную дорогу composite timber-concrete bridge деревобетонный мост concrete slab bridge мост с проезжей частью из бетон-

ных плит connecting bridge перекидной, переходной мостик curved криволинейный; дуговой; изогну-

тый cut bay пролет (моста) cutoff излучина (реки); место среза свай

-D-

dam запруживать; строить плотину; подпирать (воду); запруда; дамба; плотина; гать; насыпь; перемычка dam out отвести плотину dam site место сооружения плотины dam up подпирать (воду) плотиной damage повреждать; наносить ущерб;

расстроить; портить; поврежде-ние; ущерб; вред; убыток; рас-стройство; авария

dash and dot line пунктирная линия из черточек и

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точек («штрихпунктир») deck bridge мост с ездой поверху deck girder балочный мост с ездой поверху deck span пролетное строение (моста) с ез-

дой поверху deck stringer продольная балка проезжей части моста decking проезжая часть моста; настил

моста delivery gate водоспускное отверстие; водо-

спуск density of freight traffic грузонапряженность дороги detour bridge поворотный мост double-deck (decked) bridge двухъярусный мост (с ездой по-

верху и понизу) double-draw bridge двукрылый разводной мост double-leaf swing bridge двукрылый поворотный мост draw разводная часть моста draw bridge разводной мост draw span разводной пролет (моста) driving hammer свайный молот dry bridge мост через суходол

-Е- elevated approach насыпь (эстакада) при подходе к

мосту; рампа; подход к мосту elevated beach береговая терраса elevated railway железная дорога на эстакаде embankment насыпь; вал; дамба; гать; набе-

режная emergency bridge временный мост end bearing pile свая-стойка end pier крайняя опора (моста) end-post портальная стойка (моста) erosion эрозия; размыв; выветривание; разъедание erosional features размываемость (грунта) ever frozen subsoil вечномерзлый грунт expansion bearing подвижная опора (моста)

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-F- fabricated structure сооружение из заранее изготовленных элементов factor of safety коэффициент безопасности; запас

прочности; failure due to scouring размыв; промоина fairway arch мостовая арка для прохода судов;

судоходный пролет арочного моста

fall падать; оседать; обливаться; разрушаться; падение; склон; ук-лон; обрыв; покатость; продоль-ный уклон пути

fall of stream падение поверхности водотока; уклон водотока

falling-in of bank оползень fender pier береговая опора моста ferry переправа (через реку); паром fill заполнять; наполнять; засыпать; насыпь; засыпка; подсыпка fill construction устройство насыпи fill dam земляная плотина fill section профиль насыпи (поперечный) flag мостить плитняком; тонкий слой

породы; плитняк; плита; лещадь flat gradient пологий уклон floating bridge наплавной мост; паром floating crane плавучий кран floating earth плывун floating method устройство (насыпи) на плаву floating tube плавающий трубопровод flood dam дамба для защиты от наводнения flood flow разлив реки flood run off ливневый сток flood season паводок flood stage период затопления flood tide прилив (максимальный) flood water наводнение flooded condition половодье

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floor настилать (пол); пол; настил; про-езжая часть моста; дно шлюза; этаж

floor-beam (of bridge) поперечная балка проезжей части (моста)

floor depth строительная высота моста (для мостов с ездой понизу)

floor span пролет проезжей части (моста) floor system of bridge проезжая часть моста flooring устройство проезжей части (мос-

та) flowability текучесть; подвижность flush weir водоспускная плотина flying bridge переправа; паром folding bridge разводной мост foot-bridge пешеходный мост frame bridge рамный мост frame girder рамная ферма frame of bridge портальная рама моста frame superstructure рамная конструкция верхнего

строения моста framework основная конструкция; рамная

конструкция; остов; рама; каркас; пролетное строение (моста)

-G-

gantry платформа мостового крана gantry crane перегрузочный кран; мостовой

кран gantry traveller передвижной мостовой кран gib arm (of the crane) стрела (крана) girder опорная балка; прогон; перекла-

дина; ферма girder bridge балочный мост girder cross section поперечное сечение балки girder frame раскосная ферма grid-ironing установка водоспускных решеток grillage ростверк; прогоны под проезжую

часть моста

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-H- half-through bridge мост с ездой посередине hanging bridge подвесной, висячий мост hard rock tunnelling проходка тоннелей в твердых

грунтах hatch запруда; шлюзовая камера в кес-

соне high bank высокая насыпь; высокий откос; нагорный берег highway bridge мост под автомобильную дорогу high-level bridge мост с судоходным подмостовым габаритом hill-and-dale route дорога, проходящая поперек

водоразделов Howe truss ферма Гау hydraulic dam намывная плотина hydraulic excavation гидравлическая выемка грунта;

гидромеханизация земляных ра-бот

hydraulic fill насыпь, устроенная гидравличе-ским способом (намывом)

hydraulic fill dam намывная плотина hydraulic tunnel гидротехнический тоннель

-I- ice clogging ледяной затор ice glazed покрытый льдом ice in the soil почвенный лед impound запруживать воду inclined bridge косой мост inclined stair tunnel наклонный лестничный тоннель intermediate bay промежуточный пролет (моста); промежуточная плита (бетонной

дороги) intermediate deck проезжая часть моста с ездой по-

середине island type platform островная платформа

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-J- joist балка, брус, доска

-K- kerb бордюр (дорожной одежды);

бордюрный камень key ключ; шпонка; клин; замок свода keyed joint расклиненный шов knee-girder bascule раскрывающий подъемный мост с

коленчатыми балками (для косых пересечений)

knoll бугор; холм

-L-

lacing решетка мостовой фермы laminated deck bridge мост с плоской конструкцией

проезжей части lasher водослив; запруда lateral clearance горизонтальный просвет габарита

(моста) lateral strut распорка горизонтальных связей

(моста) lattice bridge решетчатый мост (с решетчатыми

фермами) launching girder монтажная кран-ферма lay-out of the bridge разбивка моста на пролеты laying укладка; прокладка (дороги);

сооружение (моста) leaf крыло раскрывающегося моста leaf bridge разводной мост leaf of bascule bridge разводная часть моста leg bridge балочный мост на береговых опо-

рах в виде стоек

lever draw bridge подъемный мост lever of crane стрела крана lift bridge подъемный мост

225

lift span подъемное пролетное строение lock gate шлюзовые ворота low deck of bridge проезжая часть моста с ездой по-

низу low truss bridge мост с ездой понизу

-M- macadam дорожное покрытие типа «мака-

дам» (щебеночная одежда); водо-связное шоссе; щебеночное шоссе

main line tunnel перегонный тоннель метрополи-тена

mains магистральные трубы; водопро-водная сеть

maintenance содержание (дороги); текущий ремонт; обслуживание; эксплуа-тация

mid-span середина пролета (моста) movable bridge разводной мост movable dam разборная плотина multi-span bridge многопролетный мост

-N- nail гвоздь; нагель narrow gauge малокалиберный; узкая колея

(ж.д.) narrow gauge railway узкоколейная железная дорога narrow waterway узкий проток воды natural angle of slope угол естественного откоса natural bituminized sandstone асфальтовый песчаник natural quarrying естественный распад горных по-

род natural road неукрепленная грунтовая дорога navvy землечерпалка network дорожная сеть newly-located road вновь протрассированная дорога noiseless pavement бесшумное дорожное покрытие non-overflow dam глухая плотина

226

non-plain tunnel неравнинный тоннель nose of pier ледорез мостового быка

-O- oblique bridge косой мост off-boarding platform островная платформа станции

метро open bridge открытый мост; мост без верхних

связей outlet выпуск; спуск; слив; выход; вы-

ходное отверстие; исток реки outwash размыв over-bridge мост над дорогой; путепровод overdamming затопление плотины overflow переливаться (через край); зали-

вать; затоплять; разливаться; пе-реполнять; стекать; выступать из берегов; ниспадать (о воде); зато-пление; наводнение; разлив

overhead crane мостовой кран -P- pass-by обходить; объезжать; обход; объ-

езд pass off the water отвести воду paving мощение; мостовая; дорожная

одежда pier column стойка мостовой опоры pier footing основание мостовой опоры pier shaft тело мостовой опоры pile bridge свайный мост pivot pier поворотный бык разводного мос-

та pivot span поворотный пролет моста plate girder bridge балочный мост со сплошными

фермами pneumatic pier мостовая опора на кессонном ос-

новании

227

pond areas затопленные места pontoon-bridge понтонный мост; наплавной мост portable frame bridge рамный мост primary lining первичная обделка тоннеля public utility tunnel коммунальный тоннель pull-back draw bridge откатный мост -Q- quantity diagram кривая объемов земляных работ quick ground плывун quiescent settling спокойное оседание (частиц

грунта в воде) -R- raft bridge наплавной мост (на плотах) raised beach намывная береговая трасса reconditioning work ремонтные работы refuge «островок безопасности» на ули-

цах с большим движением; ниша в перилах моста

reinforcement of ramps укрепление откосов (дороги) revetment покрытие; облицовка; одежда от-

косов river bank набережная реки; береговой откос road-cum-rail совмещенный мост rock abutment каменный береговой устой (мос-

та) rock tunnel тоннель, сооруженный горным

способом roller bearing roller bridge роликовый подшипник, катковая

опора (моста) running ground плывун running tunnel перегонный тоннель runway подвесная однорельсовая дорога

-S-

saddle опорная часть моста

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safeguarding bridge structure меры безопасности движения на мостах

scaffolds подмостки, леса, настил scaffold bridge эстакадный мост, эстакада scour размыв secondary lining вторичная обделка тоннеля shallow tunnel тоннель неглубокого заложения shipping tunnel судоходный тоннель short-term bridge краткосрочный мост single-leaf bascule bridge однокрылый раскрывающийся

мост single-line bridge однопутный мост skew bridge косой мост span навести мост; пролетное строе-

ние; пролет (моста); длина моста; ширина реки; расстояние между опорами (арки); хорда дуги

standing water level отметка уреза воды standpipe напорная труба steel truss bridge стальной мост со сквозными

фермами steep descent крутой спуск stream crossing on skew angle косой переход через реку stream flow водоток stream locations направление русла (реки) seam outlet устье реки stringer прогон деревянного моста subdrainage structure дренажное сооружение subfluvial tunnel подводный тоннель submarine tunnel подводный тоннель substructure нижнее строение (моста) subway подземный пешеходный переход surface weir плотина с водосливом suspended span подвесной пролет моста suspension bridge висячий мост swing bridge поворотный мост

-T- temporary bridge временный мост through-bridge мост с ездой понизу

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tilted bridge покосившийся мост (вследствие осадки опоры)

toll bridge мост с оплатой за проезд (США) top road bridge мост с ездой поверху total span длина моста traffic tunnel транспортный тоннель trellis-work bridge решетчатый мост trestle bridge мост на рамных опорах truss сквозная ферма truss-and-beam bridge мост с неразрезными фермами truss depth высота фермы truss frame раскосная ферма truss-stiffened suspension bridge висячий мост с фермами жестко-

сти tube railroad метрополитен tubular bridge закрытый мост с ездой понизу tunnel driving проходка тоннеля tunneling shield тоннельный щит (для проходки) turn bridge поворотный мост -U- uncongested traffic capacity беспрепятственный пропуск дви-

жения underbridge дорога под мостом underbridge clearance подмостовый габарит underpasses подземные переходы unhampered flow of traffic беспрепятственное движение uniform motion равномерное движение unwater осушать; откачивать unyielding point незыблемая опора up and down traffic встречное движение upkeep содержание в исправности; ре-

монт; стоимость содержания upline подъездной путь

-V- vehicular tunnel тоннель на автомобильных доро-

гах

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vertical lift bridge подъемный мост (с поднимаю-щейся вверх подъемной частью)

viaduct volume of traffic интенсивность движения; грузо-напряженность

-W- wash boring бурение с подмывом wash due to rain and flood размыв ливневыми и весенними

водами washway размыв waste water сточная вода water-break волнолом water conduit bridge акведук water constructional works гидротехнические сооружения water cured concrete бетон, выдержанный во влажном

состоянии water discharge расход воды water diversion водоотвод water drain pipe дренажная труба water erosion размыв water flushing промывка водой water front береговая линия water furrow открытая дренажная канава water gang ров water gate шлюзный затвор water jet струя воды; водоструйный water jetting подмыв струей воды water-level уровень воды; ватерпас water lodge водосток water passage водоток water power tunnel гидротехнический тоннель water-producing area водосборная площадь water-race бьеф water-resistant водостойкий water-resisting properties водостойкость; водонепроницае-

мость water supply водоснабжение; подача воды water works водопроводные сооружения waterproof seal (to the road) замыкающий водонепроницае-

мый слой (дороги)

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waterproofing гидроизоляция wayside придорожная полоса; обрез дорог weather condition factor коэффициент, учитывающий по-

годные условия weather-proof стойкий против атмосферных

влияний; невыветривающийся web стенка балки; перемычка wet excavation подводная выемка грунта wet spell период дождей; ненастье wetability смачиваемость wetted cross section живое сечение воды wire-mesh rainforcement сетчатая арматура wire suspension bridge висячий вантовый мост woven deck гибкая конструкция проезжей

части моста

-Y- yard ярд (линейная мера); двор; склад yardage distribution распределение объемов (земля-

ных масс) yielding деформация; осадка; оседание;

оседающий

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ANSWER KEYS

Part II. Text 5 page 28 III.

Across: 1 – construction 2 – arch 3 – bridge 4 – stream 5 – pier

Down: 1 – structure 2 – load 3 – beam

Part II. Text 12 page 54

V. Across:

1 – suspension 2 – span 3 – stiff 4 – chain 5 – wire 6 – load 7 – rope

Down: 1 – shift 2 – support 3 – efficiency 4 – continuous 5 – tension 6 – hanger 7 – plane

Part II. Text 14 page 65

II. A beam is said to be cantilevered when it projects outward, supported only

at one end.

Part II. Text 33 page 129 V.

1 – bottom adit 2 – temporary tunnel support 3 – shoefly 4 – top adit

5 – calotte 6 – lining 7 – central block 8 – side block

Part II. Text 37 page 138

II. This tunnel which runs under the Thames from this station was the first tun-

nel ever driven beneath the river…

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BIBLIOGRAPHY 1. Александрова Т.Ф., Демченко Л.Н. Методические указания к текстам на англий-ском языке для студентов III курса. – Изд-во СибАДИ, Омск, 1984. 2. Бахтин С.А., Демина О.А. Мосты, тоннели и метрополитены. Книга для чтения на английском языке: Учебное пособие. – СГАПС, 1996. 3. Маслыко Е.А., Бабинская П.К., Будько А.Ф., Петрова С.И. Настольная книга препо-давателя иностранного языка. – Минск: Вышэйшая школа,1999. 4. Новый большой англо-русский словарь: В 3-х т./ Апресян Ю.Д., Медникова Э.М., Петрова А.В. и др. – М.: Рус. яз., 1993. 5. Maissen, A., 'Concrete Beams Prestressed with CFRP Strands', Structural Engineering In-ternational 4, 1997. 6. English In Dialogues and Situations: Учебное пособие/ Балк Е.А., Леменев М.М. – М.: ИНФРА-М, 2001. 7. Hornby A S. Oxford Advanced Learner’s Dictionary of Current English. – England, Ox-ford University Press, 1995.

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CONTENTS

PART I. FROM THE HISTORY OF BRIDGE AND TUNNEL BUILDING………………………………………...….…….3 Text 1

The Ancient World........................................…………………………….…………….3 Text 2

Roman Arch Bridges.…………..………………………………..…………………..…3 Text 3

Asian and European Cantilever and Arch Bridges…….…….………………………...4 Text 4

The Renaissance and after……………….…………………………………………......5 Text 5

The Forth Bridge.....……………………………..………….…………………….........7 Text 6

Ancient Tunnels..........…………………………………….….….…………………….8 Text 7

From the Middle Ages to the Present………………………………….……………….9 PART II. BRIDGES AND TUNNELS…..............................................................................12 Text 1

Bridges ….....................................................................................................................12 Text 2

Constructional Works on Railways and Motorways……………………....………….15 Text 3

Bridge Crossing and Its Members….............................................................................19 Text 4

Bridges Classification…...............................................................................................22 Text 5

On Bridge Building…………............…………………………….……………….….27 Text 6

Form and Structure in Bridge Design….......................................................................29 Text 7

Timber and Masonry Bridges…....................................................................................34 Text 8

Reinforced Concrete Bridges........................................................................................38 Text 9

Deterioration of Concrete Bridge Decks………….........................….……………….42 Text 10

Metal Bridges…............................................................................................................45 Text 11

Steel and Concrete For Highway Bridges…….………….....................................…….49 Text 12

Suspension and Cable-Stayed Bridges…......................................................................52 Text 13

Supports and Footings Construction Technology.........................................................57 Text 14

Bridge Superstructure Erection.....................................................................................61

235

Text 15 Moscow Bridges............................................................................................................65

Text 16 St. Petersburg Bridges...................................................................................................69

Text 17 Novosibirsk Bridges......................................................................................................74

Text 18 Irtysh Bridge..................................................................................................................77

Text 19 New Bridge across the Volga River, Russia.................................................................79

Text 20 South Bridge over the Dnepr River in Kiev..................................................................83

Text 21 Strengthening a Road Bridge over the River Dvina......................................................86

Text 22 Bridges of Great Britain................................................................................................88

Text 23 Footbridge at Wiesbaden-Schierstein Harbour.............................................................91

Text 24 French and Swiss Bridges.............................................................................................93

Text 25 Ancient and Modern Chinese Bridges..........................................................................98

Text 26 Ounasjoki Bridge.........................................................................................................102

Text 27 A Unique Transporter Highway Bridge......................................................................104

Text 28 Bridging the Channel..................................................................................................106

Text 29 Bridge Maintenance....................................................................................................108

Text 30 Composite Materials in Bridge Repair........................................................................112

Text 31 Bridge or Tunnel.........................................................................................................119

Text 32 Tunnels Classification.................................................................................................122

Text 33 Rock Tunneling...........................................................................................................127

Text 34 Shield-Driven Tunnels................................................................................................130

Text 35 Automobile Tunnel under the Alps.............................................................................133

Text 36 The Mersey Tunnel.....................................................................................................135

Text 37 Tunneling Couch of Thames.......................................................................................137

Text 38 General Idea of the Underground................................................................................139

236

Text 39 The Underground Railway System Structures............................................................142

Text 40 Tunnel Maintenance....................................................................................................145

Text 41 Failures and Collapses of Constructional Works........................................................150

PART III. TEXTS FOR ADDITIONAL READING.....................................……………154 Breaking Barriers of Scale: A Concept for Extremely Long Span Bridges…....................................................................154 West Seattle Swing Bridge, Seattle, Washington…...............................................................159 Precast Segmental Highway Viaducts, Hawaii…...................................................................164 Talmadge Memorial Bridge, Savannah, Georgia…................................................................168 Acosta Bridge Replacement, Jacksonville, Florida…............................................................172 The Normandie Bridge, France: A New Record for Cable-Stayed Bridges…...........................................................................174 The Rainbow Bridge, Japan…................................................................................................183 The Tähtiniemi Bridge, Finland…..........................................................................................188 The Pitan Bridge, Taiwan….....................................................................................192 Roosevelt Lake Bridge, Gila County, Arizona…....................................................................196 Bridge Scour Failures…..........................................................................................................198 A New Footbridge, Austria….................................................................................................202 Is ISO 9001 Effective For Engineering Consultancies? …....................................................205 VOCABULARY …...............................................................................................................209 ANSWER KEYS...................................................................................................................227 BIBLIOGRAPHY………………………………………………………………………….228

237

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