ACI 318-11 Building Code Requirements for Structural Concrete (ACI 318-11) An ACI Standard and Commentary Reported by ACI Committee 318 First Printing August 2011 American Concrete Institute® Advancing concrete knowledge Building Code Requirements for Structural Concrete (ACI 318-11) 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. 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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 U.S.A. Phone: 248-848-3700 Fax: 248-848-3701 www.concrete.org ISBN 978-0-87031-744-6 BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318-11) AND COMMENTARY REPORTED BY ACI COMMITTEE 318 ACI Committee 318 Structural Building Code Voting Main Committee Members Randall W. Poston Basile G. Rabbat Chair Secretary Sergio M. Alcocer Anthony E. Fiorato James O. Jirsa David M. Rogowsky Neal S. Anderson Catherine E. French Dominic J. Kelly David H. Sanders Florian G. Barth Robert J. Frosch Gary J. Klein Guillermo Santana Roger J. Becker Luis E. García Ronald Klemencic Thomas C. Schaeffer Kenneth B. Bondy Satyendra Ghosh Cary S. Kopczynski Stephen J. Seguirant Dean A. Browning Harry A. Gleich Colin L. Lobo Andrew W. Taylor James R. Cagley David P. Gustafson Paul F. Mlakar Eric M. Tolles Ned M. Cleland James R. Harris Jack P. Moehle James K. Wight W. Gene Corley Terence C. Holland Gustavo J. Parra-Montesinos Sharon L. Wood Charles W. Dolan Shyh-Jiann Hwang Julio A. Ramirez Loring A. Wyllie Jr. Voting Subcommittee Members F. Michael Bartlett Kevin J. Folliard Andres Lepage Theodore A. Mize Mario E. Rodriguez Raul D. Bertero H. R. Trey Hamilton III Raymond Lui Suzanne Dow Nakaki Bruce W. Russell Allan P. Bommer R. Doug Hooton LeRoy A. Lutz Theodore L. Neff M. Saiid Saiidi JoAnn P. Browning Kenneth C. Hover Joseph Maffei Lawrence C. Novak Andrea J. Schokker Nicholas J. Carino Steven H. Kosmatka Donald F. Meinheit Viral B. Patel John F. Stanton Ronald A. Cook Michael E. Kreger Fred Meyer Conrad Paulson Roberto Stark David Darwin Jason J. Krohn Denis Mitchell Jose A. Pincheira John W. Wallace Lisa R. Feldman Daniel A. Kuchma International Liaison Members Mathias Brewer Alberto Giovambattista Hector Monzon-Despang Oscar M. Ramirez Josef Farbiarz Hector D. Hernandez Enrique Pasquel Fernando Reboucas Stucchi Luis B. Fargier-Gabaldon Angel E. Herrera Patricio A. Placencia Fernando Yáñez Consulting Members John E. Breen H. S. Lew Robert F. Mast Neil M. Hawkins James G. MacGregor Charles G. Salmon BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318-11) AND COMMENTARY REPORTED BY ACI COMMITTEE 318 PREFACE The “Building Code Requirements for Structural Concrete” (“Code”) covers the materials, design, and construction of structural concrete used in buildings and where applicable in nonbuilding structures. The Code also covers the strength evaluation of existing concrete structures. Among the subjects covered are: contract documents; inspection; materials; durability requirements; concrete quality, mixing, and placing; formwork; embedded pipes; construction joints; reinforcement details; analysis and design; strength and serviceability; flexural and axial loads; shear and torsion; development and splices of reinforcement; slab systems; walls; footings; precast concrete; composite flexural members; prestressed concrete; shells and folded plate members; strength evaluation of existing structures; provisions for seismic design; structural plain concrete; strut- and-tie modeling in Appendix A; alternative design provisions in Appendix B; alternative load and strength reduction factors in Appendix C; and anchoring to concrete in Appendix D. The quality and testing of materials used in construction are covered by reference to the appropriate ASTM standard specifications. Welding of reinforcement is covered by reference to the appropriate American Welding Society (AWS) standard. Uses of the Code include adoption by reference in general building codes, 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 portion cannot be included. The Commentary is provided for this purpose. Some of the considerations of the committee in developing the Code portion 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. 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 construction (concrete to concrete); compressive strength; concrete construction; concrete slabs; concretes; construction joints; continuity (structural); contract 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. ACI 318-11 was adopted as a standard of the American Concrete Institute shall not be liable for any loss or damage arising therefrom. Reference to May 24, 2011, to supersede ACI 318-08 in accordance with the Institute’s this Commentary shall not be made in contract documents. If items found standardization procedure and was published August 2011. in this Commentary are desired by the licensed design professional to be A complete metric companion to ACI 318 has been developed, 318M; a part of the contract documents, they shall be restated and incorporated metric equivalents are provided only in Appendix F of this document. in mandatory language. ACI Committee Reports, Manuals, Guides, Standard Practices, and Copyright © 2011, American Concrete Institute. Commentaries are intended for guidance in planning, designing, executing, All rights reserved including rights of reproduction and use in any form and inspecting construction. This Commentary is intended for the use of or by any means, including the making of copies by any photo process, or individuals who are competent to