1、 Structural Concrete: Behavior to Implementation A Symposium Honoring James G. MacGregor Editors Shuaib Ahmad Roger Green S. Ali Mirza international o SP- 198 DISCUSSION of individual papers in this symposium may be submitted in accordance with general requirements of the AC1 Publication Policy to A
2、C1 headquarters at the address given below. Closing date for submission of discussion is May 1, 2001. All discussion approved by the Technical Activities Committee along with closing remarks by the authors will be published in the September/October 2001 issue of either AC1 Structural Journal or AC1
3、Materials Journal 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,
4、or the supplier, 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 O 2001 .kME,WCAN CONCRETE INSTITUTE P.O. Box 9094 Farmington Hills, Michigan 48333-9094 All rights re
5、served including 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 de
6、vice, unless permission in writing is obtained from the copyright proprietors. Printed in the United States of America Editorial production: Jane D. Carroll Library of Congress catalog card number: 00-1 10165 ISBN: 0-87031-003-8 Leadership, combined with innovation and integrity, are qualities inher
7、ent in James G. MacGregors personal and professional activities. These attributes led a group known as the “Friends of Jim” to prepare and hold a national symposium of the American Concrete Institute in Seattle to honor Jim MacGregor. The symposium offered papers on diagonal tension, reliability, co
8、lumns, and engineering procedures and was well received. These papers have been published in the ACI Structural Journal or in this symposium volume. Papers offered for publication were reviewed according to AC1 procedures. The “Friends of Jim” began work on this volume and members of the AC1 staff a
9、bly assisted them. Without this valuable assistance, considerable delay may have resulted. Leadership is not a common quality in a modem society. Many aspire to leadership but few have the integrity, the compassion, the will to serve, or the people skills to be leaders. Such an individual is Jim Mac
10、Gregor. “The Friends of Jim” 2000 IN TRIBUTE TO JAMES GRIERSON MACGREGOR A leader in Structural Concrete Building Code Development and Education On Wednesday, April 9 1997, colleagues, students, and friends of Dr. James G. MacGregor gathered for an all-day symposium at the American Concrete Institut
11、e Convention in Seattle, Washington. The James G. MacGregor Symposium was entitled Structural Concrete Behavior and Design. The objective of the Symposium was to honor Jim MacGregor for his extensive contributions to research, to both professional and student education, to the prudent use of structu
12、ral concrete, and to ACI. The Symposium also recognized through the various presentations, the calm and effective manner in which Jim MacGregor has made these contributions. The four technical mini-sessions were planned to relate to Dr. MacGregors professional and research interests. These include S
13、tructural Reliability, Shear and Torsion in Structural Concrete, Stability of Columns and Frames, and Examples from Professional Practice. The papers presented in this Special Publication volume were an outgrowth from that Symposium. While now in residence in British Columbia where he is very active
14、 in both AC1 Building Code activities and in textbook writing, Jim MacGregor is more familiarly recognized as an Albertan. Bom in Vegreville in the Canadian Province of Alberta in February 1934, Jim received his primary, secondary, and undergraduate education in Edmonton. His father was a highly res
15、pected author there. Upon completion of his B.Sc. in Civil Engineering with Distinction degree at the University of Alberta in May 1956, Jim traveled to Champaign-Urbana where he earned M.S. (1958) and Ph.D. (1960) degrees under the tutelage of former AC1 President Chet Siess and numerous other Illi
16、nois faculty who staffed the Camelot of reinforced and prestressed concrete in the USA. Jim had the opportunity to work closely with Chet Siess on AC1 3 18 Building Code Committee proposals and was clearly infected by a lifelong desire to be of service to the concrete design and construction communi
17、ties. His personal research contributions at Illinois were notable, in particular laying the foundation for design for shear in prestressed concrete. Upon his return to the University of Alberta as a faculty member in 1960, he immersed himself in a broad range of activities that were to lead to inte
18、rnational recognition as an expert in structural concrete behavior and in quantifying structural safety. He advanced rapidly through the professional ranks, in 1985 was named a University Professor and from 1987 to 1990 served as Chair of the V Department of Civil Engineering. Throughout his career
19、he also carried out numerous consulting engineering assignments. He became a Professor Emeritus in 1994. From the time of his return to Alberta, he was quickly recognized for his ability to synthesize - to find the similarities between an important engineering problem and the material he found in th
20、eses and dissertations, reports, published papers, committee documents, and textbooks. A 1968 ASCE State-of-the-Art Award was quickly followed by another 1974 ASCE State-of-the-Art Award, again for a committee report on shear. Throughout his career, Jim excelled in turning research results into spec
21、ific AC1 and Canadian National Building Code proposals. The Code formulation proposal reflecting the synthesized shear studies earned Jim the 1976 ASCE R. C. Reese Research Prize, and a paper on design of deep beams earned the AC1 R. C. Reese Research Medal in 1987. Throughout his career, Jim has be
22、en a highly effective Technical and Building Code Committee leader. Particularly in the area of shear and torsion in reinforced and prestressed concrete, he led the adoption of design models for one- and two- way shear, integrated torsion with shear and flexure, and developed strut-and-tie models fo
23、r D-Discontinuity regions. While these developments encompassed his own tests, the latter were a small fraction of the overall base for the recommendations. AC1 awarded him the Delmar L. Bloem Award for Distinguished Service in 1974, recognizing his technical committee leadership. in paraiiei develo
24、pment, Jim continued his interest in slender columns that began while working as a research associate at Illinois. Working with the Joint ACI-ASCE Committee on Reinforced Concrete Columns, he was a principal author of the “Moment Magnifier Method” for slender column design, which in 1971 replaced th
25、e behaviorally incorrect “Load Reduction Factor” method that had historically been the accepted procedure in the AC1 Building Code. His contributions were recognized by simultaneous award of the AC1 Reese and Wason Medals in 1972 for the same paper on slenderness effects. He continues to provide lea
26、dership in improving the approximate column slenderness design procedures and in refining methods of calculation for the more “exact” second order analysis procedures. Another paper on frame stability received the ASCE Reese Award in 1979. One of Jims most lasting contributions has been in the overa
27、ll synthesis of a modem, reliability-based contribution to the philosophy of structural safety underpinning the North American concrete codes. During 1975-77, Jim undertook a traveling lectureship for the Canadian Society for Civil Engineering on the subject of “Safety and Limit States Design for Re
28、inforced Concrete.” He again synthesized a great deal of previous studies and research in these fields, giving an insightful, practical, and inspiring framework for a modem structural safety approach for structural concrete. MacGregors contributions were not only in gaining general acceptance on the
29、 philosophical level, but very importantly were on the quantification level, particularly of the variability in member resistance. These landmark studies provided the basis for the LRFD code adopted by AISC, the basic load factors adopted by the ASCE 7 load standards, and the altemate load factors a
30、nd resistance factors used in the 1995 AC1 Building Code for design of composite steel-concrete structures. Recently AC1 3 18 voted to use these recommendations as the primary load and resistance factors for all structures in the AC1 318 2002 Code. The overall limit states-structural safety philosop
31、hy has been implemented in the Canadian codes. MacGregor and his VI Co-workers at the National Bureau of Standards program received one of ASCEs highest honors, the 1983 Norman Medal for this pioneering effort. Jim Macgregors greatest contributions are the long list of highly informative and useful
32、papers that have graced the pages of major North American and international journals. Their quality has been vividly attested to by the recognition of his peers on prize committees in numerous societies. Certainly, in terms of a legacy, one must mention the capstone that Jim provided in two editions
33、 of his Prentice Hall text, Reinforced Concrete: Mechanics and Design. Its comprehensiveness combined with its originality established it as a major text in the field and an important part of the legacy of a giant among the leaders of structural concrete design practices. Truly an educator par excel
34、lence, Jim received the AC1 Kelly Award in 1986, “for research and teaching of student and practitioner.” In addition to his technical leadership, Jim has been a major figure in the administrative leadership of ACI. A past member of the Technical Activities Committee, Jim served as a member of the A
35、C1 Board of Direction (1972-75 and 1990-95), held the office of Vice President (1990-92), and was President of the Institute, serving with distinction from 1992-93. His pre-eminent stature was recognized by an honorary Doctor of Engineering awarded by Lakehead University in 1998 and an honorary Doct
36、or of Science awarded by his beloved University of Alberta in 1999. He was elected a Fellow of the Royal Society of Canada in 1992, an Honorary Member of AC1 in 2000, and has received many, many other accolades. Jim MacGregor has been the greatest living synthesist in the reinforced concrete design
37、and building regulation field. He has drawn on research in North America, Europe, and Japan to provide a basis for modem building code regulations to protect life and investment. He has an uncanny knack of being able to see proper relationships in very disparate studies. He has summarized and illust
38、rated these in highly imaginative and highly creative design proposals, which form the basis for current international standards in load factors, resistance factors, structural safety, reinforced concrete shear and torsion, and reinforced concrete slender columns and stability. Building regulations
39、throughout Canada, the United States, Mexico, South America, Australia and New Zealand and much of Southeast Asia directly use code language and procedures developed and pioneered by Jim MacGregor. Jim MacGregor complimented his structural engineering interests with an even stronger interest and ded
40、ication to his family. His wife Barbara has shared Jim with AC1 and other organizations, while remaining a strong partner in every sense of the term. She travels with Jim worldwide and helps keep him on an even keel. Their children, Bob, Joan, and Dave have given strong support and love to their par
41、ents. Tragedy struck their family when Bob was killed in a fire, taken at the height of his creativeness as a partner in a structural concrete bridge design fim. The family has grown even closer in the aftermath of tragedy. Jim and Barb enjoy hosting visits from their eight grandchildren at their lo
42、vely retirement home on the British Columbia Sunshine Coast. Jim remains an active contributor to AC1 committees and is completing the 3rd edition of Reinforced Concrete: Mechanics and Design. A long and productive career still has more chapters to unfold. CONTENTS STRUT AND TIE MODELS by D. M. Rogo
43、wsky . 1 RELIABILITY CONCEPTS AND REALISTIC DESIGN STANDARDS by R. G. Sexsmith . 15 STRUCTURAL DESIGN FOR HIGH-STRENGTH CONCRETE-IMPORTANT CODE ASPECTS by D. Mitchell . 23 SHEAR DESIGN FOR THE CONFEDERATION BRIDGE by W. H. Dilger and P. Langohr . 45 LEADING CONCRETE DESIGN CODES TO NEW HEIGHTS by J.
44、 E. Breen . 69 RELIABILITY-BASED ASSESSMENT OF CONCRETE STRENGTH IN EXISTING STRUCTURES by F. M. Bartlett 85 FLEXURAL STIFFNESS OF COMPOSITE STEEL REINFORCED CONCRETE COLUMNS by S. A. Mirza 103 NOTES ABOUT DR JAMES G. MACGREGOR 129 SP 198-1 Strut and Tie Models by D. M. Rogowsky Synopsis The evoluti
45、on of strut and tie models is reviewed and their characteristics are discussed. From their evolution it is seen that more design effort should be expended on developing a reasonable truss than on refined calculations of nodal stresses and permissible concrete stresses. Strut and tie models are desig
46、n tools. They allow engineers to put an appropriate amount of material in an appropriate place, and expeditiously demonstrate that there is at least one way for the structure to safely carry the design load. They are not very useful for checking designs. When one is planning the structural analysis,
47、 one needs to know if the design will be done on the basis of strut and tie models. Different models may be required for different load cases. Rather than modeling the whole structure, models may be applied to specific regions of a structure. Designs based on strut and tie models may require slightl
48、y more reinforcement than designs based on other methods since, in general, the contribution of concrete tensile strength is ignored. Finely tuned empirical equations will use less reinforcement but are restricted by the limits of the test data. Strut and tie models are general rational design tools
49、 that do not have such limitations. Keywords: plasticity; reinforced concrete; strut; tie 1 2 Rogowsky D M Rogowsky has been involved in the design and construction of concrete structures since 1973. As a practicing structural engineer, he used strut and tie models in the design of numerous structures over a period of some 15 years. He is currently a Professor at the University of Alberta. INTRODUCTION Strut and tie models are a useful but sometime misunderstood tool for the design and detailing of reinforced concrete structures. While rudimentary s
