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Philosophy and Organization
ACI 318-14:Reorganized for Design
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Overview
• A brief history of ACI 318
• The rationale for reorganization
• How 318-14 is organized
•
318-14 style
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History
• 1910 – first code published: “Standard Building
Regulations for the Use of Reinforced Concrete”
• Structural provisions assumed a working stress limit
through 1956
• “Ultimate Strength” approach firmly established in
1971 edition.
• AC I 318 organization based on behavior of cast-in-place reinforced concrete
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Significant changes (since 1971)
• Development lengths
• Torsional strength
• Seismic design and detailing
• Integrity reinforcement
• Concrete exposure c lasses
• Strain-based strength reduction factors
• Anchoring to concrete
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History
• 1971 Code had 750 provisions
• 2011Code has more than 2,500provisions
ACI 318-11 compared toAC I 318-71
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Overview
• A brief history of ACI 318
• The rationale for reorganization
• How 318-14 is organized
• 318-14 style
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318 Organization Since 1971
• Chapters 7 – 12 are central to organization
– Analysis
– Serviceability (Deflections, Crack Control, etc.)
– Strength (Flexure, Shear, etc.)
– Related Reinforcement Details
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ACI 318-11Organization
Δ
Anchorage, Ch. 12
Flexure, Ch. 10
Shear, Ch. 11
Deflection, Ch. 9
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318-11 Organization (since 1971)
• Specialty Chapters
– Two-way Slabs (Ch 13)
– Footings (Ch 15)
– Precast (Ch 16)
– Prestressed (Ch 18)
–
Seismic (Ch 21)
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Need to find a tool?
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ACI 318-14 Reorganization Process
2003: committee began discussion
2006: surveyed users, held focus groups / workshops
Engineers want all related information for a member’sdesign and detailing easily located
Engineers want the code to be configured parallel to howthey design members
2007: outline developed
2008: committee approved effort
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Major goals of reorganizing 318
• Find the information you need quickly
• Increase certainty that a design fully meets theCode
• Place for new information
• “Clean the G arage!”
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Overview
• A brief history of ACI 318
• The rationale for reorganization
• How 318-14 is organized
• 318-14 style
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What does 318-14 look like?
ONE-WAY
SLABS
STRUCTURAL
SYSTEMSCOLUMNS DIAPHRAGMS
FOUNDATIONS
PLAIN
CONCRETE
MEMBERS
BEAMS
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ACI 318-14 Organization
10 Parts
• General
• Analysis
• Members
• J oints/Connections/Anchors
• Seismic
• Materials &Durability
• Strength &Serviceability
• Reinforcement
• Construction
• Evaluation
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ACI 318-14 Organization
General
• 1: General
• 2: Notation and Terminology
• 3: Referenced Standards
• 4: Structural System Requirements (new)
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ACI 318-14 Organization
Analysis
• 5: Loads
• 6: Structural Analysis
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ACI 318-14 Organization
Members
• 7: One-Way Slabs
• 8: Two-Way Slabs
• 9: Beams
• 10: Columns
• 11: Walls
• 12: Diaphragms (new)
• 13: Foundations
• 14: Plain Concrete
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ACI 318-14 Organization
Typical member chapter sections
X.1 Scope
X.2 General
X.3 Design Limits
X.4 Required Strength
X.5 Design Strength
X.6 Reinforcement Limits
X.7 Reinforcement DetailingX.?
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1114ACI 318-
Organization
Δ
Anchorage,
Flexure,
Shear,
Deflection, Ch. 9
Ch. 11
Ch. 10
Ch. 12
Ch. 9
Ch. 9
Ch. 9
Ch. 9
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ACI 318-14 Organization
Joints / Connections / Anchors
15: Beam-column and slab-column joints
16: Connections between members
17: Anchoring to concrete
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ACI 318-14 Organization
Seismic
• 18: Earthquake Resistant Structures
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ACI 318-14 Organization
Materials & Durabilty
• 19: Concrete: Design and Durability Properties
• 20: Steel Reinforcement Properties, Durability, and
Embedments
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Strength & Serviceability
• 21: Strength Reduction Factors
• 22: Sectional Strength
• 23: Strut-and-Tie Models
• 24: Serviceability Requirements
ACI 318-14 Organization
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ACI 318-14 Organization
Member Chapter
9.5 — Design strength
9.5.2 — Moment
9.5.2.1 — If P u < 0.10f’ c A g ,M n shall be calculated inaccordance with 22.3.
9.5.2.2 — If P u ≥ 0.10f’ c A g ,M
n shall be calculated in
accordance with 22.4.
Toolbox Chapter
22.3 —Flexural strength…
22.4 — Axial strength orcombined flexural and
axial strength…
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Reinforcement
• 25: Reinforcement Details
ACI 318-14 Organization
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ACI 318-14 Organization
Construction
• 26: Construction Documents and Inspection
• 318 is written to the engineer, not the contrac tor.
• Construction requirements must be communicated on theconstruction documents.
• In 318-14, all construction requirements are gathered
together in Chapter 26.
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ACI 318-14 Organization
Evaluation
• 27: Strength Evaluation of Existing Structures
• Applies when strength is in doubt
• Well understood – analytical evaluation
•
Not well understood – load test
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Overview
• A brief history of ACI 318
• The rationale for reorganization
• How 318-14 is organized
• 318-14 style
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7.6.7.1— Center-to-center spacing of pretensioning
tendons at each end of a member shall be not less than
4db for strands, or 5db for wire, except that if specified
compressive strength of concrete at time of initial prestress,
fci′ , is 4000 psi or more, minimum center-to-center spacing
of strands shall be 1-3/4 in. for strands of 1/2 in. nominal
diameter or smaller and 2 in. for strands of 0.6 in. nominal
diameter. See also 3.3.2.
ACI 318-11 Style
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ACI 318-14 Style
Same requirements in a table
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ACI 318-11 Style
18.1.2 — All provisions of this Code not specificallyexcluded, and not in conflict with provisions ofChapter 18, shall apply to prestressed concrete.
18.1.3 — The following provisions of this Code shall notapply to prestressed concrete, except as specificallynoted:
as noted in 18.4.4.
Sections 6.4.4, 7.6.5, 8.12.2, 8.12.3, 8.12.4, 8.13,
10.5, 10.6, 10.9.1, and 10.9.2; Chapter 13; and Sections14.5, and 14.6, except that certain sections of 10.614.3,
apply
Chapter 18 – Prestressed Concrete
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ACI 318-14 Style
• 9.6 — Reinforcement limits
– 9.6.1— Minimum flexural reinforcement in nonprestressedbeams
– 9.6.2 — Minimum flexural reinforcement in prestressedbeams
• 9.7 — Reinforcement detailing
– 9.7.3 — Flexural reinforcement in nonprestressed beams
– 9.7.4 — Flexural reinforcement in prestressed beams
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Benefits of ACI 318-14
• Organized from a designer’s perspective
• Easier to find spec ific requirements
• Intuitive location of information
• Clarified c ross references
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Benefits of ACI 318-14
• Tables improve speed of understanding
• Consistent language in text
• Single idea for each requirement
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Technical changes
ACI 318-14:Reorganized for Design
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Chapters with no significant changes from 318-11
Ch. 2
Notation and
Terminology
Ch. 3
Referenced
Standards
Ch. 10
Columns
Ch. 11
Walls
Ch. 13
Foundations
Ch. 16
Connections
Between Members
Ch. 17
Anchoring to
Concrete
Ch. 23
Strut‐and‐Tie
Models
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What are Technical changes from 318-11?
• 1 Chapter/ 2 appendices / 2 sections removed
• Clarifications or gaps found duringreorganization
• Additions and modifications not related to the
reorganization
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Chapters / Appendices removed
• 318-11 Ch. 19, Shells and Folded PlateMembers – Moved to new ACI 318.2-14 code (reformatted but
no technical changes)
• 318-11 Appendix B - Alternative Provisions forReinforced and Prestressed Concrete Flexuraland Compression Members (ρb)
•
318-11 Appendix C - Alternate Load andStrength Reduction Factors (U = 1.4D + 1.7L)
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Sections removed
• ACI 318-11 Sect. 5.3 - Statistical
requirements for proportioning concrete
(now refers to ACI 301)
• ACI 318-11 Sect. 18.18 - Post-tensioninggrout proportioning for bonded tendon
requirements (now refers to PTI M55.1)
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Discussion of technical changes
• Remaining technical changes presented
along with reorganization
• Technical change marked with a *