1、ACI 224.4R-13Guide to Design Detailing to Mitigate CrackingReported by ACI Committee 224First PrintingDecember 2013Guide to Design Detailing to Mitigate Cracking Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in
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10、rmation: 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 Inst
11、itute38800 Country Club DriveFarmington Hills, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-848-3701www.concrete.orgISBN: 978-0-87031-856-6American Concrete InstituteAdvancing concrete knowledgeRecommendations made in this guide offer performance-based details that can mitigate and control concrete cra
12、cking. Structural elements are reviewed individually to identify crack causation and to offer design and detailing recommendations to mitigate crack development. In addition, standard details for various struc-tural members within a building are offered that have been used effectively to mitigate an
13、d control crack development in concrete members.Keywords: cast-in-place; crack mitigation; crack control; cracking; detailing; environmental structure; foundation; prestressed; reinforcement; restraint; shrinkage; slab; tensile stress; thermal effects; wall.CONTENTSCHAPTER 1INTRODUCTION AND SCOPE, p
14、. 21.1Introduction, p. 21.2Objective, p. 21.3Scope, p. 2CHAPTER 2NOTATION AND DEFINITIONS, p. 22.1Notation, p. 22.2Definitions, p. 3CHAPTER 3DESIGN-DETAILING CONSIDERATIONS, p. 33.1Concrete member type and reinforcement, p. 33.2Overall and local regions, p. 33.3Framing compatibility, p. 3CHAPTER 4DE
15、TAILING OF TWO-WAY REINFORCED CONCRETE SLAB SYSTEMS, p. 34.1General, p. 34.2Causes and types of restraint cracking, p. 34.3Crack mitigation and control, p. 5CHAPTER 5DETAILING OF ONE-WAY REINFORCED CONCRETE SLAB SYSTEMS, p. 95.1General, p. 95.2Causes and types of restraint cracking, p. 105.3Crack mi
16、tigation and control, p. 11CHAPTER 6DETAILING OF COLUMNS, p. 126.1General, p. 126.2Short columns, p. 126.3Columns between walls, p. 136.4Corner and exterior columns, p. 136.5Slender columns, p. 136.6Multistory columns, p. 136.7Column/slab joints, p. 146.8Oversized or unique-shaped columns (architect
17、ural columns), p. 14ACI 224.4R-13Guide to Design Detailing to Mitigate CrackingReported by ACI Committee 224Jeffrey S. West*, Chair Jacob K. Bice, SecretaryFlorian G. Barth*Peter H. BischoffDavid DarwinJohn F. DuntemannChristopher C. FerraroFouad H. FouadDavid W. FowlerRobert J. FroschGrant T. Halvo
18、rsenWill Hansen*Harvey H. Haynes*Mohammad IqbalRalf Leistikow*Malcolm K. LimEdward G. NawyKamran M. NematiKeith A. PashinaRandall W. Poston*Guillermo Alberto RiverosJohn W. RobertsAndrew ScanlonAndrea J. SchokkerConsulting MembersJulius G. PotyondyRoyce J. RhoadsErnest K. Schrader_*Members of the co
19、mmittee who prepared this report.Special acknowledgement to Paul Hedli for his contribution to this report.1ACI Committee Reports, Guides, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals w
20、ho 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. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not
21、 be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the
22、Architect/Engineer.ACI 224.4R-13 was adopted and published December 2013.Copyright 2013, 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, p
23、rinted, 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.CHAPTER 7DETAILING OF WALLS, p. 157.1Gravity load-bearing walls, p. 157.2Non-load-bearing walls,
24、 p. 157.3Shear walls, p. 157.4Walls intended to contain liquid, p. 15CHAPTER 8DETAILING ON SLABS-ON-GROUND, p. 168.1General, p. 168.2Contraction joints, p. 168.3Construction joints, p. 188.4Expansion and isolation joints, p. 19CHAPTER 9REFERENCES, p. 20Cited references, p. 20CHAPTER 1INTRODUCTION AN
25、D SCOPE1.1IntroductionThis guide addresses how to reduce potential cracking in reinforced concrete buildings in the design process through judicious consideration of building layout, selection of appropriate connections and joint types, and use of good rein-forcement details. Each member within a st
26、ructure may be subject to different types of cracks. Once the building design is developed, the type of framing system and its geometry selected, and appropriate code-required loads considered, it is then possible for the engineer to understand and identify the possible predominate crack development
27、, crack types, and crack locations for each member within the structure. Predicting possible crack development for members within a building typically allows application of appropriate design details to mitigate and control cracking. Effective detailing of concrete members can improve strength, serv
28、iceability (deflection and durability), and aesthetics of a concrete structure.The terms “crack mitigation” and “crack control” as used in this document have distinct meanings. Crack mitigation involves measures that are intended to prevent cracking from occurring. This includes concepts intended to
29、 minimize or eliminate restraint, such as consideration of building layout, the use of connection or element releases, or both. Crack control involves measures that are intended to control where cracks occur, or to limit the width and spacing of cracks. Crack control approaches include the use of jo
30、ints and rein-forcement detailing. The term “design details” in this docu-ment is a broad term intended to include all design measures intended to mitigate and control cracking.Some of the crack mitigation and control measures described in this document involve reinforcement details and other requir
31、ements that may already be required by the Building Code for structural reasons. Other measures recom-mended in this document may require details and reinforce-ment amounts in excess of that required by ACI 315.1.2ObjectiveThe ACI Detailing Manual (ACI Committee 315 2004) provides standard reinforce
32、ment details to aid the designer in addressing concrete cracking. The ACI Detailing Manual shows individual details in isolation, which may be used for a particular member, joint, or cross section. In contrast, the objective of this document is to address the mitigation and control of cracking by co
33、nsidering the overall nature of a structure and how members may experience additional cross-sectional stresses due to the restraint caused by the structural system. The effect of the geometry and layout of the concrete framing system on the cracking of individual members or joints is discussed, and
34、recommendations for more favorable arrangements of structural framing to mini-mize restraint are presented. Additionally, specific framing conditions where the cracking of a particular part of the structure is directly or indirectly affected by the neighboring elements or the overall framing system
35、are discussed, and suggested reinforcement and release details to avoid or mini-mize such cracking are provided.1.3ScopeThis document provides recommendations for design details and structural framing guidelines to mitigate, control, or distribute crack development in concrete members and structural
36、 systems. The recommendations and guidelines are presented in terms of concepts and effective practices that have been successfully implemented to mitigate and control cracking. Specific reinforcement details are presented for some situations, but not all, as the document is intended to illustrate c
37、oncepts and approaches rather than to provide comprehensive details for all situations.The reinforcement details shown in this document are for Grade 60 deformed steel reinforcing bars. Note that these reinforcement details may not be sufficient when other types of reinforcement are used, and in par
38、ticular where the elastic properties (for example, fiber-reinforced polymer), bond properties, or strength of the bars are different.This document specifically excludes the review of concrete member cracking due to unique or special materials used, concrete mixture proportions, or placing and finish
39、ing practices. The design details presented herein are limited to building structures and may not apply to special structures or nonbuilding structures. This document is limited to cast-in-place concrete frames only, not to precast concrete and masonry elements.CHAPTER 2NOTATION AND DEFINITIONS2.1No
40、tationS1, S2= horizontal spacing of contraction joints in slabs on ground, in. (mm)SDowel= center-to-center spacing of dowel bars used for vertical joint load transfer in slabs on ground, in. (mm)SPlate= center-to-center spacing of steel plates used for vertical joint load transfer in slabs on groun
41、d, in. (mm)r = steel reinforcement ratioAmerican Concrete Institute Copyrighted Materialwww.concrete.org2 GUIDE TO DESIGN DETAILING TO MITIGATE CRACKING (ACI 224.4R-13)2.2Definitions“2013 ACI Concrete Terminology” provides a compre-hensive list of definitions that is available online at: http:/www.c
42、oncrete.org/Tools/ConcreteTerminology.aspx.CHAPTER 3DESIGN-DETAILING CONSIDERATIONS3.1Concrete member type and reinforcementA detailed review of each concrete member type is required to mitigate or control localized and global cracking. Each member should be reviewed for its predominant cracking beh
43、avior. The most common cracks are caused by:a) Restrained concrete volume changes (creep, shrinkage, elastic shortening, and thermal effects)b) Concrete member restraint effectsc) Loading effects (flexure, shear, axial tension/compres-sion, and torsion)This guide addresses horizontal floor framing m
44、embers such as one- and two-way slab systems, vertical elements of concrete structures such as walls and columns, and nonstructural slabs-on-ground. This guide may call for minimum reinforcement in excess of that noted in ACI 318 for increased serviceability performance.3.2Overall and local regionsD
45、ue to the variety of member types and geometries and the various factors that cause cracks, it is imperative that each concrete member be reviewed individually and as part of the overall framing system during the design-detailing process. Concentrated load application and vulnerable member joint con
46、ditions may require a localized review of concrete details. On the other hand, the overall framing layout may cause indirect load transfer due to geometry or member incompatibility that results in concrete cracking based on overall behavior of the framing system. Chapters 4 through 8 describe a loca
47、lized and overall performance review of members.3.3Framing compatibilityFraming compatibility is one of the basic premises of a properly performing structure. The relative proportioning of member shapes plays an important role in mitigating concrete cracking. An example of framing incompatibility wo
48、uld be found in a structure where concrete member sizes are simply out of scale, such as where oversized architec-tural columns are used to support a thin slab. The restraining effects of oversized members on their surrounding members can be significant. For this reason, it is advisable to main-tain
49、 compatible member sizes and connections to mitigate restraint cracking during concrete shortening. If geometry or architectural considerations dictate such incompatibility, special consideration should be given to incompatible member connections. Alternatively, incompatible framing geometry resulting from architectural considerations can be addressed by using built-up nonstructural foam sections or shapes added to the completed concrete frame to obtain the architectural shapes desired (for example, to increase column size fo
