Cracked moment of inertia aci 318 14

DESIGN

4 Building Code Requirements for Structural Concrete (ACI 318M-14) and Commentary (ACI 318RM-14) Reported by ACI Committee 318

An ACI Standard

Building Code Requirements for Structural Concrete (ACI 318M-14)

An ACI Standard

Commentary on Building Code Requirements for Structural Concrete (ACI 318RM-14)

An ACI Report

Reported by ACI Committee 318

Randall W. Poston, Chair Basile G. Rabbat, Secretary

VOTING MAIN COMMITTEE MEMBERS

Neal S. Anderson Florian G. Barth Roger J. Becker

Kenneth B. Bondy Dean A. Browning James R. Cagley Ned M. Cleland

W. Gene Corley* Ronald A. Cook

Charles W. Dolan

Anthony E. Fiorato Catherine E. French

Robert J. Frosch Luis E. Garcia

Brian C. Gerber S. K. Ghosh

David P. Gustafson James R. Harris

Terence C. Holland Shyh-Jiann Hwang

James O. Jirsa Dominic J. Kelly

Gary J. Klein Ronald Klemencic Cary Kopczynski

Colin L. Lobo Paul F. Mlakar Jack P. Moehle

Lawrence C. Novak Gustavo J. Parra-Montesinos

David M. Rogowsky David H. Sanders Guillermo Santana

Thomas C. Schaeffer Stephen J. Seguirant Andrew W. Taylor

James K. Wight Sharon L. Wood

Loring A. Wyllie Jr.

VOTING SUBCOMMITTEE MEMBERS

Raul D. Bertero Allan P. Bommer John F. Bonacci Patricio Bonelli Sergio F. Breña

JoAnn P. Browning Nicholas J. Carino

David Darwin Jeffrey J. Dragovich Kenneth J. Elwood Lisa R. Feldman

Harry A. Gleich H. R. Trey Hamilton

R. Doug Hooton Kenneth C. Hover

Steven H. Kosmatka Michael E. Kreger

Jason J. Krohn Daniel A. Kuchma

Andres Lepage Raymond Lui LeRoy A. Lutz

Joe Maffei Donald F. Meinheit

Fred Meyer Suzanne Dow Nakaki

Theodore L. Neff Viral B. Patel

Conrad Paulson Jose A. Pincheira

Carin L. Roberts-Wollmann Mario E. Rodríguez

Bruce W. Russell

M. Saiid Saiidi Andrea J. Schokker

John F. Silva John F. Stanton Roberto Stark

Bruce A. Suprenant John W. Wallace W. Jason Weiss

Fernando V. Yáñez

INTERNATIONAL LIAISON MEMBERS

F. Michael Bartlett Mathias Brewer Josef Farbiarz

Luis B. Fargier-Gabaldon Alberto Giovambattista

Hector Hernandez

Angel E. Herrera Hector Monzon-Despang

Enrique Pasquel

Patricio A. Placencia Oscar M. Ramirez

Fernando Reboucas Stucchi

CONSULTING MEMBERS

Sergio M. Alcocer John E. Breen

Neil M. Hawkins H. S. Lew

James G. MacGregor Robert F. Mast

Julio A. Ramirez Charles G. Salmon*

ACI 318M-14 supersedes ACI 318M-11, and published March 2015. Copyright © 2015, American Concrete Institute.

All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduc- tion or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.

1

*Deceased.

First Printing March 2015

ISBN: 978-1-942727-11-8

Building Code Requirements for Structural Concrete and Commentary

Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of ACI.

The technical committees responsible for ACI committee reports and standards strive to avoid ambiguities, omissions, and errors in these documents. In spite of these efforts, the users of ACI documents occasionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions for the improvement of ACI documents are requested to contact ACI via the errata website at http://concrete.org/Publications/ DocumentErrata.aspx. Proper use of this document includes periodically checking for errata for the most up-to-date revisions.

ACI committee documents are intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. Individuals who use this publication in any way assume all risk and accept total responsibility for the application and use of this information.

All information in this publication is provided “as is” without warranty of any kind, either express or implied, including but not limited to, the implied warranties of merchantability, fitness for a particular purpose or non-infringement.

ACI and its members disclaim liability for damages of any kind, including any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost profits, which may result from the use of this publication.

It is the responsibility of the user of this document to establish health and safety practices appropriate to the specific circumstances involved with its use. ACI does not make any representations with regard to health and safety issues and the use of this document. The user must determine the applicability of all regulatory limitations before applying the document and must comply with all applicable laws and regulations, including but not limited to, United States Occupational Safety and Health Administration (OSHA) health and safety standards.

Participation by governmental representatives in the work of the American Concrete Institute and in the development of Institute standards does not constitute governmental endorsement of ACI or the standards that it develops.

Order information: ACI documents are available in print, by download, on CD-ROM, through electronic subscription, or reprint and may be obtained by contacting ACI.

Most ACI standards and committee reports are gathered together in the annually revised ACI Manual of Concrete Practice (MCP).

American Concrete Institute 38800 Country Club Drive Farmington Hills, MI 48331 Phone: +1.248.848.3700 Fax: +1.248.848.3701

www.concrete.org

PREFACE TO ACI 318M-14 The “Building Code Requirements for Structural Concrete” (“Code”) provides minimum requirements for the materials,

design, and detailing of structural concrete buildings and, where applicable, nonbuilding structures. This Code addresses struc- tural systems, members, and connections, including cast-in-place, precast, plain, nonprestressed, prestressed, and composite construction. Among the subjects covered are: design and construction for strength, serviceability, and durability; load combi- nations, load factors, and strength reduction factors; structural analysis methods; deflection limits; mechanical and adhesive anchoring to concrete; development and splicing of reinforcement; construction document information; field inspection and testing; and methods to evaluate the strength of existing structures. “Building Code Requirements for Concrete Thin Shells” (ACI 318.2) is adopted by reference in this Code.

The Code user will find that ACI 318-14 has been substantially reorganized and reformatted from previous editions. The principal objectives of this reorganization are to present all design and detailing requirements for structural systems or for indi- vidual members in chapters devoted to those individual subjects, and to arrange the chapters in a manner that generally follows the process and chronology of design and construction. Information and procedures that are common to the design of members are located in utility chapters.

The quality and testing of materials used in construction are covered by reference to the appropriate ASTM standard speci- fications. Welding of reinforcement is covered by reference to the appropriate American Welding Society (AWS) standard.

Uses of the Code include adoption by reference in a general building code, and earlier editions have been widely used in this manner. The Code is written in a format that allows such reference without change to its language. Therefore, background details or suggestions for carrying out the requirements or intent of the Code provisions cannot be included within the Code itself. The Commentary is provided for this purpose.

Some of the considerations of the committee in developing the Code are discussed within the Commentary, with emphasis given to the explanation of new or revised provisions. Much of the research data referenced in preparing the Code is cited for the user desiring to study individual questions in greater detail. Other documents that provide suggestions for carrying out the requirements of the Code are also cited.

Technical changes from ACI 318-11 to ACI 318-14 are outlined in the May 2014 issue of Concrete International. Transition keys showing how the code was reorganized are provided on the ACI website on the 318 Resource Page under

Topics in Concrete.

KEYWORDS admixtures; aggregates; anchorage (structural); beam-column frame; beams (supports); building codes; cements; cold

weather construction; columns (supports); combined stress; composite construction (concrete and steel); composite construc- tion (concrete to concrete); compressive strength; concrete construction; concrete slabs; concretes; construction joints; conti- nuity (structural); construction documents; contraction joints; cover; curing; deep beams; deflections; earthquake-resistant structures; embedded service ducts; flexural strength; floors; folded plates; footings; formwork (construction); frames; hot weather construction; inspection; isolation joints; joints (junctions); joists; lightweight concretes; load tests (structural); loads (forces); materials; mixing; mixture proportioning; modulus of elasticity; moments; pipe columns; pipes (tubing); placing; plain concrete; precast concrete; prestressed concrete; prestressing steels; quality control; reinforced concrete; reinforcing steels; roofs; serviceability; shear strength; shear walls; shells (structural forms); spans; splicing; strength; strength analysis; stresses; structural analysis; structural concrete; structural design; structural integrity; T-beams; torsion; walls; water; welded wire reinforcement.

NOTES FROM THE PUBLISHER ACI Committee Reports, Guides, and Commentaries are intended for guidance in planning, designing, executing, and

inspecting construction. This commentary (318RM-14) is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the information it contains. ACI disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising there from. Reference to this commentary shall not be made in construction documents. If items found in this commentary are desired by the Architect/ Engineer to be a part of the construction documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer.

The materials, processes, quality control measures, and inspections described in this document should be tested, monitored, or performed as applicable only by individuals holding the appropriate ACI Certification or equivalent.

ACI 318M-14, Building Code Requirements for Structural Concrete, and ACI 318RM-14, Commentary, are presented in a side-by-side column format. These are two separate but coordinated documents, with Code text placed in the left column and the corresponding Commentary text aligned in the right column. Commentary section numbers are preceded by an “R” to further distinguish them from Code section numbers.

The two documents are bound together solely for the user’s convenience. Each document carries a separate enforceable and distinct copyright.

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BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14) 3

INTRODUCTION

This Commentary discusses some of the considerations of Committee 318 in developing the provisions contained in “Building Code Requirements for Structural Concrete (ACI 318-14),” hereinafter called the Code or the 2014 Code. Emphasis is given to the explanation of new or revised provisions that may be unfamiliar to Code users. In addition, comments are included for some items contained in previous editions of the Code to make the present commentary inde- pendent of the previous editions. Comments on specific provisions are made under the corresponding chapter and section numbers of the Code.

The Commentary is not intended to provide a complete historical background concerning the development of the Code, nor is it intended to provide a detailed résumé of the studies and research data reviewed by the committee in formulating the provisions of the Code. However, references to some of the research data are provided for those who wish to study the background material in depth.

As the name implies, “Building Code Requirements for Structural Concrete” is meant to be used as part of a legally adopted building code and as such must differ in form and substance from documents that provide detailed specifica- tions, recommended practice, complete design procedures, or design aids.

The Code is intended to cover all buildings of the usual types, both large and small. Requirements more stringent than the Code provisions may be desirable for unusual construction. The Code and Commentary cannot replace sound engineering knowledge, experience, and judgment.

A building code states only the minimum requirements necessary to provide for public health and safety. The Code is based on this principle. For any structure, the owner or the licensed design professional may require the quality of materials and construction to be higher than the minimum requirements necessary to protect the public as stated in the Code. However, lower standards are not permitted.

The Commentary directs attention to other documents that provide suggestions for carrying out the requirements and intent of the Code. However, those documents and the Commentary are not a part of the Code.

The Code has no legal status unless it is adopted by the government bodies having the police power to regulate building design and construction. Where the Code has not been adopted, it may serve as a reference to good practice even though it has no legal status.

The Code provides a means of establishing minimum standards for acceptance of designs and construction by legally appointed building officials or their designated repre- sentatives. The Code and Commentary are not intended for

use in settling disputes between the owner, engineer, archi- tect, contractor, or their agents, subcontractors, material suppliers, or testing agencies. Therefore, the Code cannot define the contract responsibility of each of the parties in usual construction. General references requiring compli- ance with the Code in the project specifications should be avoided since the contractor is rarely in a position to accept responsibility for design details or construction require- ments that depend on a detailed knowledge of the design. Design-build construction contractors, however, typically combine the design and construction responsibility. Gener- ally, the contract documents should contain all of the neces- sary requirements to ensure compliance with the Code. In part, this can be accomplished by reference to specific Code sections in the project specifications. Other ACI publica- tions, such as “Specifications for Structural Concrete (ACI 301)” are written specifically for use as contract documents for construction.

It is recommended to have testing and certification programs for the individual parties involved with the execu- tion of work performed in accordance with this Code. Avail- able for this purpose are the plant certification programs of the Precast/Prestressed Concrete Institute, the Post-Tensioning Institute, and the National Ready Mixed Concrete Associa- tion; the personnel certification programs of the American Concrete Institute and the Post-Tensioning Institute; and the Concrete Reinforcing Steel Institute’s Voluntary Certifica- tion Program for Fusion-Bonded Epoxy Coating Applicator Plants. In addition, “Standard Specification for Agencies Engaged in Construction Inspecting and/or Testing” (ASTM E329-09) specifies performance requirements for inspection and testing agencies.

Design reference materials illustrating applications of the Code requirements may be found in the following docu- ments. The design aids listed may be obtained from the sponsoring organization.

Design aids: “ACI Design Handbook,” Publication SP-17(11), Amer-

ican Concrete Institute, Farmington Hills, MI, 2011, 539 pp. (This provides tables and charts for design of eccentrically loaded columns by the Strength Design Method of the 2009 Code. Provides design aids for use in the engineering design and analysis of reinforced concrete slab systems carrying loads by two-way action. Design aids are also provided for the selection of slab thickness and for reinforcement required to control deformation and assure adequate shear and flexural strengths.)

For a history of the ACI Building Code, see Kerekes, F., and Reid, H. B., Jr., “Fifty Years of Development in Building Code Requirements for Reinforced Concrete,” ACI Journal, V. 50, No. 6, Feb. 1954, p. 441. For a discussion of code philosophy, see Siess, C. P., “Research, Building Codes, and Engineering Practice,” ACI Journal, V. 56, No. 5, May 1960, p. 1105.

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4 BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14)

“ACI Detailing Manual—2004,” ACI Committee 315, Publication SP-66(04), American Concrete Institute, Farm- ington Hills, MI, 2004, 212 pp. (Includes the standard, ACI 315-99, and report, ACI 315R-04. Provides recommended methods and standards for preparing engineering drawings, typical details, and drawings placing reinforcing steel in rein- forced concrete structures. Separate sections define respon- sibilities of both engineer and reinforcing bar detailer.)

“Guide to Durable Concrete (ACI 201.2R-08),” ACI Committee 201, American Concrete Institute, Farmington Hills, MI, 2008, 49 pp. (This describes specific types of concrete deterioration. It contains a discussion of the mech- anisms involved in deterioration and the recommended requirements for individual components of the concrete, quality considerations for concrete mixtures, construction procedures, and influences of the exposure environment.)

“Guide for the Design and Construction of Durable Parking Structures (362.1R-12),” ACI Committee 362, American Concrete Institute, Farmington Hills, MI, 2012, 24 pp. (This summarizes practical information regarding design of parking structures for durability. It also includes information about design issues related to parking structure construction and maintenance.)

“CRSI Handbook,” Concrete Reinforcing Steel Institute, Schaumburg, IL, tenth edition, 2008, 777 pp. (This provides tabulated designs for structural elements and slab systems. Design examples are provided to show the basis and use of the load tables. Tabulated designs are given for beams; square, round, and rectangular columns; one-way slabs; and one-way joist construction. The design tables for two-way slab systems include flat plates, flat slabs, and waffle slabs. The chapters on foundations provide design tables for square footings, pile caps, drilled piers (caissons), and cantilevered retaining walls. Other design aids are presented for crack control and development of reinforcement and lap splices.)

“Reinforcement Anchorages and Splices,” Concrete Reinforcing Steel Institute, Schaumburg, IL, fifth edition, 2008, 100 pp. (This provides accepted practices in splicing reinforcement. The use of lap splices, mechanical splices,

and welded splices are described. Design data are presented for development and lap splicing of reinforcement.)

“Structural Welded Wire Reinforcement Manual of Standard Practice,” Wire Reinforcement Institute, Hart- ford, CT, eighth edition, Apr. 2010, 35 pp. (This describes welded wire reinforcement material, gives nomenclature and wire size and weight tables. Lists specifications and prop- erties and manufacturing limitations. Book has latest code requirements as code affects welded wire. Also gives devel- opment length and splice length tables. Manual contains customary units and soft metric units.)

“Structural Welded Wire Reinforcement Detailing Manual,” Wire Reinforcement Institute, Hartford, CT, 1994, 252 pp. (The manual, in addition to including ACI 318 provisions and design aids, also includes: detailing guid- ance on welded wire reinforcement in one-way and two-way slabs; precast/prestressed concrete components; columns and beams; cast-in-place walls; and slabs-on-ground. In addition, there are tables to compare areas and spacings of high-strength welded wire with conventional reinforcing.)

“PCI Design Handbook—Precast and Prestressed Concrete,” Precast/Prestressed Concrete Institute, Chicago, IL, seventh edition, 2010, 804 pp. (This provides load tables for common industry products, and procedures for design and analysis of precast and prestressed elements and struc- tures composed of these elements. Provides design aids and examples.)

“Design and Typical Details of Connections for Precast and Prestressed Concrete,” Precast/Prestressed Concrete Institute, Chicago, IL, second edition, 1988, 270 pp. (This updates available information on design of connections for both structural and architectural products, and presents a full spectrum of typical details. This provides design aids and examples.)

“Post-Tensioning Manual,” Post-Tensioning Insti- tute, Farmington Hills, MI, sixth edition, 2006, 354 pp. (This provides comprehensive coverage of post-tensioning systems, specifications, design aids, and construction concepts.)

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BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14) 5

TABLE OF CONTENTS

PART 1: GENERAL

CHAPTER 1 GENERAL

1.1—Scope of ACI 318, p. 9 1.2—General, p. 9 1.3—Purpose, p. 10 1.4—Applicability, p. 10 1.5—Interpretation, p. 11 1.6—Building official, p. 12 1.7—Licensed design professional, p. 13 1.8—Construction documents and design records, p. 13 1.9—Testing and inspection, p. 13 1.10—Approval of special systems of design, construction,

or alternative construction materials, p. 13

CHAPTER 2 NOTATION AND TERMINOLOGY

2.1—Scope, p. 15 2.2—Notation, p. 15 2.3—Terminology, p. 30

CHAPTER 3 REFERENCED STANDARDS

3.1—Scope, p. 45 3.2—Referenced standards, p. 45

CHAPTER 4 STRUCTURAL SYSTEM REQUIREMENTS

4.1—Scope ,p. 49 4.2—Materials, p. 49 4.3—Design loads, p. 49 4.4—Structural system and load paths, p. 49 4.5—Structural analysis, p. 52 4.6—Strength, p. 52 4.7—Serviceability, p. 53 4.8—Durability, p. 53 4.9—Sustainability, p. 53 4.10—Structural integrity, p. 54 4.11—Fire resistance, p. 54 4.12—Requirements for specific types of construction,

p. 54 4.13—Construction and inspection, p. 56 4.14—Strength evaluation of existing structures, p. 56

PART 2: LOADS & ANALYSIS

CHAPTER 5 LOADS

5.1—Scope, p. 57 5.2—General, p. 57 5.3—Load factors and combinations, p. 58

CHAPTER 6 STRUCTURAL ANALYSIS

6.1—Scope, p. 63 6.2—General, p. 63 6.3—Modeling assumptions, p. 68 6.4—Arrangement of live load, p. 69 6.5—Simplified method of analysis for nonprestressed

continuous beams and one-way slabs, p. 70 6.6—First-order analysis, p. 71 6.7—Elastic second-order analysis, p. 79 6.8—Inelastic second-order analysis, p. 81 6.9—Acceptability of finite element analysis, p. 81

PART 3: MEMBERS

CHAPTER 7 ONE-WAY SLABS

7.1—Scope, p. 83 7.2—General, p. 83 7.3—Design limits, p. 83 7.4—Required strength, p. 85 7.5—Design strength, p. 85 7.6—Reinforcement limits, p. 86 7.7—Reinforcement detailing, p. 88

CHAPTER 8 TWO-WAY SLABS

8.1—Scope, p. 93 8.2—General, p. 93 8.3—Design limits, p. 94 8.4—Required strength, p. 97 8.5—Design strength, p. 102 8.6—Reinforcement limits, p. 103 8.7—Reinforcement detailing, p. 106 8.8—Nonprestressed two-way joist systems, p. 117 8.9—Lift-slab construction, p. 118 8.10—Direct design method, p. 118 8.11—Equivalent frame method, p. 124

CHAPTER 9 BEAMS

9.1—Scope, p. 129 9.2—General, p. 129 9.3—Design limits, p. 130 9.4—Required strength, p. 132 9.5—Design strength, p. 134 9.6—Reinforcement limits, p. 136 9.7—Reinforcement detailing, p. 140 9.8—Nonprestressed one-way joist systems, p. 149 9.9—Deep beams, p. 151

CHAPTER 10 COLUMNS

10.1—Scope, p. 153 10.2—General, p. 153 10.3—Design limits, p. 153

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6 BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14)

10.4—Required strength, p. 154 10.5—Design strength, p. 155 10.6—Reinforcement limits, p. 156 10.7—Reinforcement detailing, p. 157

CHAPTER 11 WALLS

11.1—Scope, p. 163 11.2—General, p. 163 11.3—Design limits, p. 164 11.4—Required strength, p. 164 11.5—Design strength, p. 165 11.6—Reinforcement limits, p. 168 11.7—Reinforcement detailing, p. 169 11.8—Alternative method for out-of-plane slender wall

analysis, p. 171

CHAPTER 12 DIAPHRAGMS

12.1—Scope, p. 173 12.2—General, p. 173 12.3—Design limits, p. 175 12.4—Required strength, p. 175 12.5—Design strength, p. 178 12.6—Reinforcement limits, p. 185 12.7—Reinforcement detailing, p. 185

CHAPTER 13 FOUNDATIONS

13.1—Scope, p. 187 13.2—General, p. 189 13.3—Shallow foundations, p. 192 13.4—Deep foundations, p. 193

CHAPTER 14 PLAIN CONCRETE

14.1—Scope, p. 195 14.2—General, p. 196 14.3—Design limits, p. 196 14.4—Required strength , p. 198 14.5—Design strength, p. 199 14.6—Reinforcement detailing, p. 202

PART 4: JOINTS/CONNECTIONS/ANCHORS

CHAPTER 15 BEAM-COLUMN AND SLAB-COLUMN JOINTS

15.1—Scope, p. 203 15.2—General, p. 203 15.3—Transfer of column axial force through the floor

system, p. 203 15.4—Detailing of joints, p. 204

CHAPTER 16 CONNECTIONS BETWEEN MEMBERS

16.1—Scope, p. 205 16.2—Connections of precast members, p. 205 16.3—Connections to foundations, p. 209

16.4—Horizontal shear transfer in composite concrete flexural members, p. 212

16.5—Brackets and corbels, p. 214

CHAPTER 17 ANCHORING TO CONCRETE

17.1—Scope, p. 221 17.2—General, p. 222 17.3—General requirements for strength of anchors, p. 228 17.4—Design requirements for tensile loading, p. 234 17.5—Design requirements for shear loading, p. 247 17.6—Interaction of tensile and shear forces, p. 258 17.7—Required edge distances, spacings, and thicknesses

to preclude splitting failure, p. 258 17.8—Installation and inspection of anchors, p. 260

PART 5: EARTHQUAKE RESISTANCE

CHAPTER 18 EARTHQUAKE-RESISTANT STRUCTURES

18.1—Scope, p. 263 18.2—General, p. 263 18.3—Ordinary moment frames, p. 269 18.4—Intermediate moment frames, p. 269 18.5—Intermediate precast structural walls, p. 274 18.6—Beams of special moment frames, p. 275 18.7—Columns of special moment frames, p. 280 18.8—Joints of special moment frames, p. 285 18.9—Special moment frames constructed using precast

concrete, p. 289 18.10—Special structural walls, p. 292 18.11—Special structural walls constructed using precast

concrete, p. 304 18.12—Diaphragms and trusses, p. 304 18.13—Foundations, p. 310 18.14—Members not designated as part of the seismic-

force-resisting system, p. 312

PART 6: MATERIALS & DURABILITY

CHAPTER 19 CONCRETE: DESIGN AND DURABILITY REQUIREMENTS

19.1—Scope, p. 315 19.2—Concrete design properties, p. 315 19.3—Concrete durability requirements, p. 316 19.4—Grout durability requirements, p. 324

CHAPTER 20 STEEL REINFORCEMENT PROPERTIES, DURABILITY, AND EMBEDMENTS

20.1—Scope, p. 325 20.2—Nonprestressed bars and wires, p. 325 20.3—Prestressing strands, wires, and bars, p. 330 20.4—Structural steel, pipe, and tubing for composite

columns, p. 333 20.5—Headed shear stud reinforcement, p. 334

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BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14) 7

20.6—Provisions for durability of steel reinforcement, p. 334

20.7—Embedments, p. 339

PART 7: STRENGTH & SERVICEABILITY

CHAPTER 21 STRENGTH REDUCTION FACTORS

21.1—Scope, p. 341 21.2—Strength reduction factors for structural concrete

members and connections p. 341

CHAPTER 22 SECTIONAL STRENGTH

22.1—Scope, p. 347 22.2—Design assumptions for moment and axial strength,

p. 347 22.3—Flexural strength, p. 349 22.4—Axial strength or combined flexural and axial

strength, p. 350 22.5—One-way shear strength, p. 351 22.6—Two-way shear strength, p. 360 22.7—Torsional strength, p. 371 22.8—Bearing, p. 378 22.9—Shear friction, p. 380

CHAPTER 23 STRUT-AND-TIE MODELS

23.1—Scope, p. 385 23.2—General, p. 386 23.3—Design strength, p. 392 23.4—Strength of struts, p. 392 23.5—Reinforcement crossing bottle-shaped struts, p. 394 23.6—Strut reinforcement detailing, p. 395 23.7—Strength of ties, p. 395 23.8—Tie reinforcement detailing, p. 396 23.9—Strength of nodal zones, p. 397

CHAPTER 24 SERVICEABILITY REQUIREMENTS

24.1—Scope, p. 399 24.2—Deflections due to service-level gravity loads, p. 399 24.3—Distribution of flexural reinforcement in one-way

slabs and beams, p. 403 24.4—Shrinkage and temperature reinforcement, p. 405 24.5—Permissible stresses in prestressed concrete flexural

members, p. 407

PART 8: REINFORCEMENT

CHAPTER 25 REINFORCEMENT DETAILS

25.1—Scope, p. 411 25.2—Minimum spacing of reinforcement, p. 411 25.3—Standard hooks, seismic hooks, crossties, and

minimum inside bend diameters, p. 412

25.4—Development of reinforcement, p. 414 25.5—Splices, p. 428 25.6—Bundled reinforcement, p. 433 25.7—Transverse reinforcement, p. 434 25.8—Post-tensioning anchorages and couplers, p. 443 25.9—Anchorage zones for post-tensioned tendons, p. 443

PART 9: CONSTRUCTION

CHAPTER 26 CONSTRUCTION DOCUMENTS AND INSPECTION

26.1—Scope, p. 453 26.2—Design criteria, p. 455 26.3—Member information, p. 455 26.4—Concrete materials and mixture requirements, p. 455 26.5—Concrete production and construction, p. 462 26.6—Reinforcement materials and construction

requirements, p. 468 26.7—Anchoring to concrete , p. 472 26.8—Embedments, p. 473 26.9—Additional requirements for precast concrete , p. 473 26.10—Additional requirements for prestressed concrete,

p. 474 26.11—Formwork, p. 476 26.12—Concrete evaluation and acceptance, p. 478 26.13—Inspection, p. 483

PART 10: EVALUATION

CHAPTER 27 STRENGTH EVALUATION OF EXISTING STRUCTURES

27.1—Scope, p. 487 27.2—General, p. 487 27.3—Analytical strength evaluation, p. 488 27.4—Strength evaluation by load test, p. 489 27.5—Reduced load rating, p. 492

REFERENCES & APPENDICES

COMMENTARY REFERENCES

APPENDIX A STEEL REINFORCEMENT INFORMATION

APPENDIX B EQUIVALENCE BETWEEN SI-METRIC, MKS-METRIC, AND U.S. CUSTOMARY UNITS OF NONHOMOGENOUS EQUATIONS IN THE CODE

INDEX

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8 BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14)

CHAPTER 1—GENERAL

1.1—Scope of ACI 318 1.1.1 This chapter addresses (a) through (h):

(a) General requirements of this Code (b) Purpose of this Code (c) Applicability of this Code (d) Interpretation of this Code (e) Definition and role of the building official and the licensed design professional (f) Construction documents (g) Testing and inspection (h) Approval of special systems of design, construction, or alternative construction materials

1.2—General 1.2.1 ACI 318, “Building Code Requirements for Struc-

tural Concrete,” is hereafter referred to as “this Code.”

1.2.2 In this Code, the general building code refers to the building code adopted in a jurisdiction. When adopted, this Code forms part of the general building code.

1.2.3 The official version of this Code is the English language version, using inch-pound units, published by the American Concrete Institute.

1.2.4 In case of conflict between the official version of this Code and other versions of this Code, the official version governs.

1.2.5 This Code provides minimum requirements for the materials, design, construction, and strength evaluation of structural concrete members and systems in any structure designed and constructed under the requirements of the general building code.

1.2.6 Modifications to this Code that are adopted by a particular jurisdiction are part of the laws of that jurisdic- tion, but are not a part of this Code.

1.2.7 If no general building code is adopted, this Code provides minimum requirements for the materials, design, construction, and strength evaluation of members and systems in any structure within the scope of this Code.

R1—GENERAL

R1.1—Scope of ACI 318 R1.1.1 This Code includes provisions for the design

of concrete used for structural purposes, including plain concrete; concrete containing nonprestressed reinforcement, prestressed reinforcement, or both; composite columns with structural steel shapes, pipes, or tubing; and anchoring to concrete.

This Code is substantially reorganized from the previous version, ACI 318M-11. This chapter includes a number of provisions that explain where this Code applies and how it is to be interpreted.

R1.2—General

R1.2.2 The American Concrete Institute recommends that this Code be adopted in its entirety.

R1.2.3 Committee 318 develops the Code in English, using inch-pound units. Based on that version, Committee 318 approved three other versions:

(a) In English using SI units (ACI 318M) (b) In Spanish using SI units (ACI 318S) (c) In Spanish using inch-pound units (ACI 318SUS).

Jurisdictions may adopt ACI 318, ACI 318M, ACI 318S, or ACI 318SUS.

R1.2.5 This Code provides minimum requirements and exceeding these minimum requirements is not a violation of the Code.

The licensed design professional may specify project requirements that exceed the minimum requirements of this Code.

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1.3—Purpose 1.3.1 The purpose of this Code is to provide for public

health and safety by establishing minimum requirements for strength, stability, serviceability, durability, and integrity of concrete structures.

1.3.2 This Code does not address all design considerations.

1.3.3 Construction means and methods are not addressed in this Code.

1.4—Applicability 1.4.1 This Code shall apply to concrete structures designed

and constructed under the requirements of the general building code.

1.4.2 Applicable provisions of this Code shall be permitted to be used for structures not governed by the general building code.

1.4.3 The design of thin shells and folded plate concrete structures shall be in accordance with ACI 318.2, “Building Code Requirements for Concrete Thin Shells.”

1.4.4 This Code shall apply to the design of slabs cast on stay-in-place, noncomposite steel decks.

1.4.5 For one- and two-family dwellings, multiple single- family dwellings, townhouses, and accessory structures to

R1.3—Purpose R1.3.1 This Code provides a means of establishing

minimum requirements for the design and construction of structural concrete, as well as for acceptance of design and construction of concrete structures by the building officials or their designated representatives.

This Code does not provide a comprehensive statement of all duties of all parties to a contract or all requirements of a contract for a project constructed under this Code.

R1.3.2 The minimum requirements in this Code do not replace sound professional judgment or the licensed design professional’s knowledge of the specific factors surrounding a project, its design, the project site, and other specific or unusual circumstances to the project.

R1.4—Applicability

R1.4.2 Structures such as arches, bins and silos, blast- resistant structures, chimneys, underground utility struc- tures, gravity walls, and shielding walls involve design and construction requirements that are not specifically addressed by this Code. Many Code provisions, however, such as concrete quality and design principles, are applicable for these structures. Recommendations for design and construc- tion of some of these structures are given in the following: • “Code Requirements for Reinforced Concrete Chim-

neys and Commentary” (ACI 307-08) • “Standard Practice for Design and Construction of

Concrete Silos and Stacking Tubes for Storing Granular Materials” (ACI 313-97)

• “Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary” (ACI 349)

• “Code for Concrete Containments” (ACI 359)

R1.4.4 In its most basic application, the noncomposite steel deck serves as a form, and the concrete slab is designed to resist all loads, while in other applications the concrete slab may be designed to resist only the superimposed loads. The design of a steel deck in a load-resisting application is given in “Standard for Non-Composite Steel Floor Deck” (SDI NC). The SDI standard refers to this Code for the design and construction of the structural concrete slab.

R1.4.5 ACI 332 addresses only the design and construc- tion of cast-in-place footings, foundation walls supported on

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10 BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318M-14) AND COMMENTARY (ACI 318RM-14)

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these types of dwellings, the design and construction of cast- in-place footings, foundation walls, and slabs-on-ground in accordance with ACI 332 shall be permitted.

1.4.6 This Code does not apply to the design and installa- tion of concrete piles, drilled piers, and caissons embedded in ground, except as provided in (a) or (b):

(a) For portions in air or water, or in soil incapable of providing adequate lateral restraint to prevent buckling throughout their length (b) For structures assigned to Seismic Design Categories D, E, and F

1.4.7 This Code does not apply to design and construction of slabs-on-ground, unless the slab transmits vertical loads or lateral forces from other portions of the structure to the soil.

1.4.8 This Code does not apply to the design and construc- tion of tanks and reservoirs.

1.4.9 This Code does not apply to composite design slabs cast on stay-in-place composite steel deck. Concrete used in the construction of such slabs shall be governed by this Code, where applicable. Portions of such slabs designed as reinforced concrete are governed by this Code.

1.5—Interpretation 1.5.1 The principles of interpretation in this section shall

apply to this Code as a whole unless otherwise stated.

continuous footings, and slabs-on-ground for limited resi- dential construction applications. Multiple single-family dwellings include structures such as townhomes.

R1.4.6 The design and installation of concrete piles fully embedded in the ground is regulated by the general building code. Recommendations for concrete piles are given in ACI 543R. Recommendations for drilled piers are given in ACI 336.3R. Recommendations for precast prestressed concrete piles are given in “Recommended Practice for Design, Manufacture, and Installation of Prestressed Concrete Piling” (PCI 1993).

Refer to 18.13.4 for supplemental requirements for concrete piles, drilled piers, and caissons in structures assigned to Seismic Design Categories D, E, and F.

R1.4.7 Detailed recommendations for design and construction of slabs-on-ground and floors that do not transmit vertical loads or lateral forces from other portions of the structure to the soil, and residential post-tensioned slabs-on-ground, are given in the following publications: • ACI 360R presents information on the design of slabs-

on-ground, primarily industrial floors and the slabs adjacent to them. The report addresses the planning, design, and detailing of the slabs. Background informa- tion on the design theories is followed by discussion of the soil support system, loadings, and types of slabs. Design methods are given for structural plain concrete, reinforced concrete, shrinkage-compensating concrete, and post-tensioned concrete slabs.

• The Post-Tensioning Institute (DC 10.5-12) provides standard requirements for post-tensioned slab-on- ground foundations, soil investigation, design, and anal- ysis of post-tensioned residential and light commercial slabs on expansive soils.

R1.4.8 Requirements and recommendations for the design and construction of tanks and reservoirs are given in ACI 350, ACI 334.1R, and ACI 372R.

R1.4.9 In this type of construction, the steel deck serves as the positive moment reinforcement. The design and construction of concrete-steel deck slabs is described in “Standard for Composite Steel Floor Deck-Slabs” (SDI C). The standard refers to the appropriate portions of this Code for the design and construction of the concrete portion of the composite assembly. SDI C also provides guidance for design of composite-concrete-steel deck slabs. The design of negative moment reinforcement to create continuity at supports is a common example where a portion of the slab is designed in conformance with this Code.

R1.5—Interpretation

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1.5.2 This Code consists of chapters and appendixes, including text, headings, tables, figures, footnotes to tables and figures, and referenced standards.

1.5.3 The Commentary consists of a preface, introduction, commentary text, tables, figures, and cited publications. The Commentary is intended to provide contextual informa- tion, but is not part of this Code, does not provide binding requirements, and shall not be used to create a conflict with or ambiguity in this Code.