Concrete The Reinforced Design Manual

The ReinforcedConcreteDesignManualIn Accordance with ACI 318-11SP-17(11) Vol 1

ACI SP-17(11)Volume 1THE REINFORCED CONCRETEDESIGN MANUALin Accordance with ACI Strut-and-tiePublication:SP-17(11)1Editors:Ronald JanowiakMichael KregerAntonio Nanni

First PrintingAugust 2012THE REINFORCED CONCRETE DESIGN MANUALEighth EditionCopyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not bereproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storagemedia, 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 orrequirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users whohave suggestions for the improvement of ACI documents are requested to contact ACI via the errata Web site atwww.concrete.org/committees/errata.asp. Proper use of this document includes periodically checking for erratafor the most up-to-date revisions.ACI committee documents are intended for the use of individuals who are competent to evaluate the significanceand limitations of its content and recommendations and who will accept responsibility for the application of thematerial it contains. Individuals who use this publication in any way assume all risk and accept total responsibilityfor 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, includingbut 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 thispublication.It is the responsibility of the user of this document to establish health and safety practices appropriate to thespecific circumstances involved with its use. ACI does not make any representations with regard to health andsafety issues and the use of this document. The user must determine the applicability of all regulatory limitationsbefore 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 developmentof 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, orreprint and may be obtained by contacting ACI.Most ACI standards and committee reports are gathered together in the annually revised ACI Manual of ConcretePractice (MCP).American Concrete Institute38800 Country Club DriveFarmington Hills, MI ing Editor: Khaled NahlawiProduction Editor: Carl BischofProduction: Barry BerginManufacturing: Marie Fullerwww.concrete.orgISBN-13: 978-0-87031-769-9ISBN-10: 0-87031-769-5

FOREWORDThe Reinforced Concrete Design Manual [SP-17(11)] is intended to provide guidance and assistance toprofessionals engaged in the design of cast-in-place reinforced concrete structures.The first Reinforced Concrete Design Manual (formerly titled ACI Design Handbook) was developed inaccordance with the design provisions of 1963 ACI 318 Building Code by ACI Committee 340, DesignAids for Building Codes, whose mission was to develop handbook editions in accordance with the ACI318 Building Code. That committee published revised editions of the handbook in accordance with the1971, 1977, 1983, and 1995 ACI 318 Building Codes. Many individuals and members of ACI Committee340 contributed to the earlier editions of the handbook, which remains the basis for the current Reinforced Concrete Design Manual. Their contributions, as well as the administrative and technical assistance from ACI staff, are acknowledged. This earlier handbook format was a collection of design aidsand illustrative examples, generated in the pre-calculator era. Many of these earlier design aids intendedto carry out relatively simple design calculations were eliminated in the SP-17(09) edition. Explanatorytext was added to each chapter, while maintaining relevant design aids and illustrative examples.The 2012 edition of the Reinforced Concrete Design Manual [SP-17(11)] was developed in accordancewith the design provisions of ACI 318-11, and is consistent with the format of SP-17(09). Chapters 1through 6 were developed by individual authors, as indicated on the first page of those chapters, andupdated to the content of ACI 318-11 as needed. Those authors were members of the former ACICommittee 340. SP-17(09) was reviewed and approved by ACI’s Technical Activities Committee(TAC).Three new chapters were developed by ACI staff engineers under the auspices of TAC for SP-17(11):Chapter 7 (Deflection); Chapter 8 (Strut-and-Tie Model); and Chapter 9 (Anchoring to Concrete). Toprovide immediate oversight and guidance for this project, TAC appointed three content editors: RonaldJanowiak, Michael Kreger, and Antonio Nanni. Their reviews and suggestions improved this publicationand are appreciated. TAC also appreciates the comments provided by Ronald Cook, Catherine French,Gary Klein, and John Silva for Chapters 8 and 9.SP-17(11) is published in two volumes: Chapters 1 through 8 are published in Volume 1 and Chapter 9 ispublished in Volume 2.Khaled NahlawiManaging Editor

On the cover:The Grand Rapids Art Museum (GRAM) received a Gold-level certification in the Leadership inEnergy and Environmental Design (LEED ) Rating System of the U.S. Green Building Council(USGBC). With that achievement, the GRAM has earned the distinction of being the first newlybuilt art museum certified under the LEED for New Construction (LEED-NC) Version 2.1requirements. The second highest of the four levels in the LEED Rating System, Gold certificationrecognizes a superior level of energy and environmental performance.Architects: wHY ArchitectureLocation: Grand Rapids, MIClient: Grand Rapids Art MuseumArea: 125,000 ft2Construction start: 2004Completion: 2007General contractors: Rockford/Pepper ConstructionConcrete contractor: Grand River ConstructionStructural Engineer: Dewhurst Macfarlane and PartnersEnvironmental Engineer: Atelier Ten/Design Plus, Inc.Lighting Consultant: Isometrix Lighting DesignCurtain Wall Consultant: W.J. Higgins & AssociatesLandscape Design: Design PlusPhoto courtesy of Steve Hall Hedrich Blessing.

ACI SP-17(11)1THE REINFORCED CONCRETE DESIGN MANUALin Accordance with ACI 318-11Volume 1Editors: Ronald Janowiak, Michael Kreger, and Antonio NanniCONTENTSChapter 1—Design for flexure. 71.1—Introduction . 71.2—Nominal and design flexural strengths (Mn and φMn) . 71.2.1—Rectangular sections with tension reinforcement . 71.2.2—Rectangular sections with compression reinforcement .81.2.3—T-sections . 91.3—Minimum flexural reinforcement. 101.4—Placement of reinforcement in sections . 101.4.1—Minimum spacing of longitudinal reinforcement . 101.4.2—Concrete protection for reinforcement . 101.4.3—Maximum spacing of flexural reinforcement and crack control . 111.4.4—Skin reinforcement . 111.5—Flexure examples . 12Flexure Example 1: Calculation of tension reinforcement area for a rectangular tension-controlled cross section. 12Flexure Example 2: Calculation of nominal flexural strength of a rectangular beam subjected to positive bending . 13Flexure Example 3: Calculation of tension reinforcement area for a rectangular cross section in the transition zone . 14Flexure Example 4: Selection of slab thickness and area of flexural reinforcement . 15Flexure Example 5: Calculation of tension and compression reinforcement area for a rectangularbeam section subjected to positive bending. 16Flexure Example 6: Calculation of tension reinforcement area for a T-section subjected to positivebending, behaving as a rectangular section . 18Flexure Example 7: Computation of the tension reinforcement area for a T-section, subjected to positivebending, behaving as a tension-controlled T-section . 19Flexure Example 8: Calculation of the area of tension reinforcement for an L-beam section,subjected to positive bending behaving as an L-section in the transition zone . 20Flexure Example 9: Placement of reinforcement in the rectangular beam section designed in Flexure Example 1 . 22Flexure Example 10: Placement of reinforcement in the slab section designed in Flexure Example 4 . 23ACI Committee Reports, Guides, Manuals, and Commentariesare intended for guidance in planning, designing, executing,and inspecting construction. This document is intended for theuse of individuals who are competent to evaluate thesignificance and limitations of its content and recommendationsand who will accept responsibility for the application of thematerial it contains. The American Concrete Institute disclaimsany and all responsibility for the stated principles. The Instituteshall not be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocuments. If items found in this document are desired by theArchitect/Engineer to be a part of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.ACI SP-17(11) supersedes ACI SP-17(09) and was adopted and published August2012.Copyright 2012, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic ormechanical device, printed, written, or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission inwriting is obtained from the copyright proprietors.1

2REINFORCED CONCRETE DESIGN MANUAL IN ACCORDANCE WITH ACI 318-11—SP-17(11)11.6—Flexure design aids .24Flexure 1: Flexural coefficients for rectangular beams with tension reinforcement; fy 60,000 psi.24Flexure 2: Flexural coefficients for rectangular beams with tension reinforcement; fy 60,000 psi.25Flexure 3: Flexural coefficients for rectangular beams with tension reinforcement; fy 75,000 psi.26Flexure 4: Flexural coefficients for rectangular beams with tension reinforcement; fy 75,000 psi.27Flexure 5: Reinforcement ratio ρ′ for compression reinforcement .28Flexure 6: T-beam construction and definition of effective flange width .29Flexure 7: Reinforcement ratio ρf (%) balancing concrete in overhang(s) in T- or L-beams; fy 60,000 psi.30Flexure 8: Reinforcement ratio ρf (%) balancing concrete in overhang(s) in T- or L-beams; fy 75,000 psi.31Flexure 9: Bar spacing and cover requirements.32Flexure 10: Skin reinforcement .

with the design provisions of ACI 318-11, and is consistent with the format of SP-17(09). Chapters 1 through 6 were developed by individual authors, as indicated on the first page of those chapters, and updated to the content of ACI 318-11 as needed. Those authors were members of the former ACI Committee 340.