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1、A C 1 SP-133 92 m 0662949 0505430 4T2 m DESIGNING CONCRETE STRUCTURES FOR SERVICEABILITY AND SAFETY n U U Eward G. Nawy Andrew Scanlon Editors n n am SP-133 COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concr
2、ete Institute) Licensed by Information Handling Services A C 1 SP-133 92 D Ob62949 0505411 339 DESIGNING CONCRETE STRUCTURES FOR SERVICEABILITY AND SAFETY Edward G. Nawy Andrew Scanlon Editors a m SP-133 COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Servi
3、ces COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 SP-133 92 Ob62949 0505432 275 DISCUSSION of individual papers in this symposium may be submitted in accordance with general requirements of the AC1 Publication Policy to AC1 headquarters at
4、the address given below. Closing date for submission of discussion is March 1, 1993. Ail discussion approved by the Technical Activities Committee along with closing remarks by the authors will be published in the September/October 1993 issue of either AC1 Structurai Journal or AC1 Materials Journal
5、 depending on the subject emphasis of the individual paper. The Institute is not responsible for the statements or opinions expressed in its publications. Institute publications are not able to, nor intended to, supplant individual training, responsibility, or judgment of the user, or the supplier,
6、of the information presented. The papers in this volume have been reviewed under Institute publication procedures by individuals expert in the subject areas of the papers. Copyright * 1992 AMERICAN CONCRETE INSTITUTE P.O. Box 19150, Redford Station Detroit, Michigan 48219 Ail rights reserved includi
7、ng rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless p
8、ermission in writing is obtained from the copyright proprietors. Printed in the United States of America Editorial production Victoria Lunick Library of Congress catalog card number 92-73234 COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT
9、 ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 SP-333 92 Obb2949 0505433 303 Design for serviceability and safety is central to the work of struc- tural engineers, code-writing bodies and the users. The current era of high strength materials, exotic
10、additives and limit states of design has neces- sitated better control of constructed facilities in their short and long-term behavior at service load and at ultimate load. This Special Publication con- centrates on topics that give the design engineer and contractor an insight into haw to avoid pra
11、ctices that could affect the integrity or long-term performance of structural elements and systems. The text is the outgrowth of a national symposium of the American Concrete Institute Co-sponsored by AC1 Committees 348 and 435, and covers topics ranging from crack-control in reinforced and prestres
12、sed concrete, safety provisions in design codes and practical deflection com- putations to limit state design principles and seismic performance of frame structures. Several papers that could not be presented due to time limi- tations are included. The papers dealing with serviceability, highlight r
13、equirements of the AC1 Codes and Reports in addition to relevant state of the art devel- opments. The papers covering safety deal with issues ranging from phil- osophical discussions of treatment of safety in codes to project case studies. Overlap is expected since serviceability and safety are indi
14、visible. All the papers presented in this publication were reviewed by re- cognized experts in accordance with the AC1 review procedures. It is hoped that designers, constructors and codifying bodies will be able to draw on the material presented in improving the safety and long-term cracking and de
15、- flection behavior of concrete constructed facilities. I PREFACE I Edward G. Nawy, P.E. Chairman, AC1 Committee 435 Andrew Scanlon, S.E. Chairman, AC1 Committee 348 .,. 111 COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI Internationa
16、l (American Concrete Institute) Licensed by Information Handling Services A C 1 SP-I133 92 m Obb2949 0505414 048 m AC1 Committee 435 DEFLECTION OF CONCRETE BUILDING STRUCTURES Edward G. Nawy Chairman John W. Eglaston Secretary Emin A. Aktan Alex Aswad Finley A. Charney Robert G. Drysdale Ahmed S. Ez
17、eldin Anis Farah Russell S. Fling Amin Ghali Sayendra K. Ghosh Anand B. Gogate Jacob S. Grossman Hidayat N. Grouni Cheng-Tzu Hsu James K. Iverson Shivaprasad Kudlapur Bernard L. Meyers M. Saeed Mirza Michael V. Pregnoff Charles G. Salmon Andrew Scanlon A. Fattah Shaikh Himat T. Solanki Maher K. Tadr
18、os Frank J. Vecchio Stanley C. Woodson AC1 Committee 348 STRUCTURAL SAFETY Andrew Scanlon Chairman Mir M. Ali Bila1 M. Ayyub Charles L. Baliou Zdenek P. Bazant Karen C. Chou Ross B. Corotis Bruce Ellingwood Luis F. Estenssoro Luis Esteva Anis Farah Dan M. Frangopol Otto C. Guedelhoefer Dan J. Gullak
19、sen Howard H.M. Hwang H.S. Lew Andrzej S. Nowak Emilio Rosenblueth Robert G. Sexsmith Laurence E. Svab Sami W. Tabsh Ronald E. Vaughn Lev Zetlin COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institut
20、e) Licensed by Information Handling Services A C 1 SP-133 92 0662949 0505415 TY . PREFACE . 111 MACRO-CRACKING AND CRACK CONTROL IN CONCRETE STRUCTURES - A STATE OF THE ART- byE.G.Nawy . 1 SAFETY PROVISIONS IN DESIGN CODES FOR REINFORCED CONCRETE STRUCTURES by A. Scanlon and R.B. Corotis . 33 INTEGR
21、ATING THE DESIGN FOR SAFETY AND SERVICEABILITY by M.Z Cobn and Z. Lounis . 45 PRACTICAL CONSIDERATIONS IN COMPUTING DEFLECTION OF REINFORCED CONCRETE by R.S. Fling 69 I CONTENTS SERVICEABILITY DESIGN IN CURRENT AUSTRALIAN CODE byB.V.Rangan 93 ALLOWABLE DEFLECTIONS: THE OTHER SIDE OF THE EQUATION by
22、A. Scanlon and L. Pinheiro 111 DESIGN AND SERVICEABILITY OF REINFORCED CONCRETE FLOOR SYSTEMS by S.J. Sopko 121 GENERALIZED RELIABILITY ASSESSMENT STRUCTURAL SAFETY AND SERVICEABILITY by I.A. Alvi and B.M. Ayyub . 133 AND RELIABILITY-BASED DESIGN FOR V COPYRIGHT ACI International (American Concrete
23、Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 SP-133 92 m 0662949 050541b 910 m EARLY AGE SHEAR-FRICTION BEHAVIOR OF HIGH-STRENGTH CONCRETE LAYERED SYSTEMS AT SUB-FREEZING TEMPERATURES by
24、 S.T. Kudlapur and E.G. Nawy 159 SENSITIVITY ANALYSIS OF DAMAGED CONCRETE BRIDGE GIRDERS by S.W. Tabsh . 187 EXPERIENCE WITH PRE- AND POST-CRACKING DEFLECTIONS OF PRETENSIONED MEMBERS byA.Aswad . 207 DESIGN FOR SAFETY, SERVICEABILITY AND DAMAGE TOLERABILITY by D.M. Frangopol and M. Klisinski . 225 E
25、VALUATION AND ANALYSIS OF HAMMERHEAD-TYPE PIER CAPS by C.C. Fu, J. Colville, and D.R. Schelling . 255 by W.B. Cranston . 277 REFLECTIONS ON LIMIT STATE DESIGN A NUMERICAL MODEL OF FLAT-PLATE TO COLUMN CONNECTION BEHAVIOR by H. Omar and G. Morris 299 SEISMIC PERFORMANCE OF CODE-DESIGNED REINFORCED CO
26、NCRETE FRAME STRUCTURES by H.H.M. Hwang and H.M. Hsu SI (metric) TABLES . 343 . 321 INDEX 345 vi COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C
27、 1 SP-133 92 = 0bb2949 0505417 857 SP 133-1 Macro-Cracking and Crack Control in Concrete Structures -A State of the Art- by E.G. Nawy Svnopsis: This paper presents the state of the art in evaluating flexural crack development and control of macro-cracking. It is based on extensive research over the
28、past five decades in the United States and overseas in the area of macro-cracking in reinforced and prestressed concrete beams and two-way action slabs and plates. With the advent of limit states theories that generally lead to economic proportioning of members, control of cracking has become essent
29、ial in order to maintain the integrity and aesthetics of concrete structures. The trend is stronger than ever in better utilization of current concrete strengths, use of higher strength concretes, including super-strength concretes of 2. psi (138 MPa) compressive strength and higher, and increased a
30、pplication of prestressed concrete concepts. All these trends require closer control of serviceability requirements in cracking and deflection. Design expressions are given for the control of cracking in reinforced concrete beams and thick one-way slabs. prestressed pretensioned and post-tensioned f
31、langed beams and reinforced concrete two-way action structural floor slabs and plates. In addition, recommendations are given for the waximum tolerable flexural crack widths in concrete elements. Keywords: Beams (supports); concretes; cover; cracking (fracturing); crack propagation; crack width and
32、spacine; flexural strendh; fracture properties; macrocrackins; microcracking; post tensioning; prestressing; pretensioning; reinforced concrete; shrinkage; stabilization; volume change 1 COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI
33、 International (American Concrete Institute) Licensed by Information Handling Services I A C 1 SP-133 92 D Obb29q7 0505q18 793 2 Nawy Edward G. Nawy. FACI. is Professor of Civil Engineering, Rutgers, The State University of New Jersey, holding the distinguished professor rand (Professor I I ) . Acti
34、ve in AC1 since 1949. Prof. Nawy is a former chairman and current member of AC1 Committee 224, Cracking, and is currently a member of AC1 Committee 340, Strength DEsign Aids for AC1 Building Codes. Chairman of AC1 Committee 435. Deflection of Concrete Building Structures; member of Joint ACI-ASCE Co
35、mmittee 421, Design of Reinforced Concrete Slabs; the Concrete Materials Research Council; Technical Activities committee of PCI, and the Tall Buildings Council. His research interests are in reinforced and prestressed concrete, particularly in the areas of crack control and serviceability behavior.
36、 Dr. Nawy has published more than 115 papers and is the author of three major textbooks: Reinforced Concrete - A Fundamental Amroach. (translated into Spanish and Chinese), Simplified Reinforced Concrete, and Prestressed Concrete - A Fundamental Amroach as well as numerous handbook chapters. He hold
37、s many honors and awards, including the AC1 Chapter Activities Committee and Henry L Kennedy Awards, was twice President of the N.J. AC1 chapter, served Honorary Vice President of the RILEM 30th Anniversary Congress, and is Honorary Professor of NIT. the Nanjing Institute of Technology. He is consul
38、tant to major engineering organizations i n the New York-New Jersey metropolitan area, and is a registered Professional Engineer in New Jersey, New York, Pennsylvania and California, and chartered engineer in England and the Commonweal th. I two terms on the Rutgers University Board of Governors, wa
39、s 1NTRom10N Presently, the trend is stronger than ever in better utilization of concrete strength by use of super strength concretes of U3, psi (138 MPa) compressive strength and higher, use of high strength reinforcement, more prestressed concretes and increased use of limit states theories. These
40、trends impose closer control of serviceability requirements which include cracking and deflection. Hence, knowledge of the mechanism of cracking in concrete elements becomes essential. Concrete cracks early in its loading history. Most cracks are a result of the following actions to which concrete c
41、an be subjected: 1. Volumetric change caused by Plastic and drying shrinkage, creep under sustained load, thermal stresses and chemical incompatibility of concrete ingredients. COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI Internati
42、onal (American Concrete Institute) Licensed by Information Handling Services A C 1 SP-133 92 m Obb2949 05054l19 b2T m Serviceability and Safety 3 2 . Stress due to bending, shear and other moments caused by transverse loads. 3. Direct stress due to applied loads or reactions or internal stress due t
43、o continuity, reversible fatigue load, long-term deflection, camber in prestressed systems, environmental effects, or differential movement i n structural systems. While the net result of these three actions is the formation of cracks, the mechanisms of their development cannot be considered identic
44、al. Volumetric change generates internal microcracking. which may develop into full cracking. Whereas, internal stresses due to applied loads could either generate internal microcracking. such as in fatigue due to load reversal, or flexural macrocracking leading to fully developed cracking. This pap
45、er concentrates on the macro-cracking aspect of cracking behavior. Yet it is important to briefly discuss micro-cracking. MICROCRACKING Micro-cracking can be classified into two main categories: a ) bond cracks at the aggregate-mortar interface, b) paste cracks within the mortar matrix. Interfacial
46、bond cracks are caused by interface shear and tensile stresses due to early volumetric change without the presence of external load. Volume change caused by hydration and shrinkage could create tensile and bond stresses of sufficient magnitude as to cause failure at the aggregate-mortar interface (1
47、). As external loads are applied, mortar cracks develop due to an increase in compressive stresses, propagating continuously through the cement matrix up to failure. Figure 1 is a typical schematic diagram that shows the nonlinear stress-strain relationship developed early in the stress history, sta
48、rting with bond micro-cracking. While extensive work exists in the area of cracking due to volumetric change, the need is apparent for additional research on creep effects on micro-cracking and for the development of a universally acceptable fracture theory to interrelate the nonlinear behavioral fa
49、ctors resulting i n crack propagation. The damage to cement paste seems to play a significant role in controlling the stress-strain relationship in concrete. The coarse aggregate particles act as stress-raisers that decrease the strength of the cement paste. As a result, micro-cracks develop that can only be detected by large magnification. The importance of additional work lies not only in the evaluation of the micro-cracks. but also i n their significance on the development of macro-cracks which generate from those micro-cracked centers of plasticity. COPYRIGHT ACI International