Module 1 Poston

8/20/2019 Module 1 Poston

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WWW.CONC RETE.ORG/ACI318 1

Philosophy and Organization

ACI 318-14:Reorganized for Design


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


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


Overview




• 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


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)

WWW.CONCRETE.ORG/AC I318 10

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


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




• 318-14 style


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



General

• 1: General

• 2: Notation and Terminology

• 3: Referenced Standards

• 4: Structural System Requirements (new)


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Analysis

• 5: Loads

• 6: Structural Analysis



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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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.?


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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Joints / Connections / Anchors

15: Beam-column and slab-column joints

16: Connections between members

17: Anchoring to concrete



Seismic

• 18: Earthquake Resistant Structures


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Materials & Durabilty

• 19: Concrete: Design and Durability Properties

• 20: Steel Reinforcement Properties, Durability, and

Embedments


Strength & Serviceability

• 21: Strength Reduction Factors

• 22: Sectional Strength

• 23: Strut-and-Tie Models

• 24: Serviceability Requirements



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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…


Reinforcement

• 25: Reinforcement Details



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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.



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




• 318-14 style


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


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


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


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


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)


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 *