ACI SP-194-2000 The Adam Neville Symposium Creep and Shrinkage - Structural Design Effects《Adam Neville讨论会 徐变和收缩.结构设计影响》.pdf

1、iaaei Obb2949 0552489 872 U The Adam Neville 4ymposium: Creep and hrinkage - Structural Design a.* Effects I 111 Ob62949 0552490 594 9 Adam Neville Symposium: Creep and Shrinkage- Structural Design Effects Editor Akthem Al-Manaseer international SP-194 .II Ob62949 0552493 420 H DISCUSSION ofindividu

2、al papers in this symposium may be submitted in accordance with general requirements of the AC1 Publication Policy to AC1 headquarters at the address given below. Closing date for submission of discussion is Nov. 1 , 2000. All discussion approved by the Technical Activi- ties Committee along with cl

3、osing remarks by the authors will be published in the JanuaryRebruary 200 1 issue of either AC1 Structural Journal or AC1 Ma- terials Journal depending on the subject ofthe individual paper. The Institute is not responsible for the statements or opinions expressed in its publications. Institute publ

4、ications are not able to, nor intended to, supplant individual training, rcsponsibility, or judgment of the user, or the supplier, of the information presented. The papers in this volume have been reviewed under Institute publication proceedures by individuals expert in the subject areas of the pape

5、rs. Copyright O 2000 AMERICAN CONCREIE NSTITUTE P.O. Box 9094 Farmington Hills, Michigan 48333-9094 All rights reserved including rights ofreproduction 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 writ

6、ten or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyrights propri- etors. Printed in the United States ofAmerica Editorial production: Greyden Press Library of Congress Card Number

7、: 00-104032 W Obb2949 0552492 3b PREFACE ABOUT ADAM NEVILLE This book is dedicated to Adam Neville and contains the papers presented at the Adam Neville Symposium held at the AC1 Convention in Atlanta in November 1997. This begs the question: why a symposium on creep honoring Adam Neville? The answe

8、r goes a long way back, but then, Neville goes a long way back too. Afier World War II service in Iraq, Persia, Palestine, and the Italian Campaign (where he was decorated for bravery) Neville enrolled at Queen Mary College, University of London, where he graduated with first class honors (correspon

9、ding to summa cum laude) in engineering in 1950. This was the period when prestressed concrete in England was in its infancy. During his final year, Neville undertook an experimental research project on prestress losses in beams. This project involved losses due to the creep of concrete and gave Nev

10、ille a taste for that little researched Although Neville won a scholarship to work toward a Ph.D., he decided to move into the world of real engineering. He firmly holds the view that academic engineers who lack practical experience of design and construction, run the risk of doing excellent researc

11、h to answer questions that are not posed by practitioners. Nevertheless, creep got under his skin, and Neville worked on his own on research dealing with the creep of concrete and obtained a M.S. and a Ph.D. from the University of London. Later as a faculty member, he continued his research and wrot

12、e numerous papers on factors influencing creep as well as its structural effects. This combination reflects Nevilles firm belief that a study of material behavior should be linked to the study of structural behavior, and that a dichotomy between materials specialists and structural specialists is un

13、likely to serve the engineering profession well. Further degrees awarded for his research were a Doctor of Science in Engineering from the University of London and a Doctor of Science from the University of Leeds, England. Nevilles interest in creep of concrete has a fairly wide-ranging effect. Whil

14、e Head of the Department of Civil Engineering at the University of Leeds, he involved a number of colleagues in research on creep, which continues to this day. While at the University of Calgary, Canada, Neville and his colleagues coauthored joint papers and books. One of the earliest books on creep

15、 of concrete, published in 1970, was titled Creep of Concrete: Plain, Reinforced, and Prestressed, by A. M. Neville. Four chapters of its 622 pages were written in collaboration with W. H. Dilger. In 1983 Neville coauthored a book with W. H. Dilger, and J. J. Brooks titled Creep of Plain and Structu

16、ral Concrete. Nevilles research covers a broad field of concrete topics. His book titled Properties of Concrete, first published in 1963, with the final edition published in 1995, is lightheartedly referred to as the concrete bible. Translated into 13 languages, this book has sold more than half a m

17、illion copies worldwide. Nevilles research has not been limited to the properties of concrete. In the 1960s and 1970s he wrote a number of papers dealing with shear in reinforced and prestressed concrete. In addition, Neville has coauthored several other successful books including Basic Statistical

18、Methods for Engineers and Scientists with J. B. Kennedy and Structural Analysis: A Uned Classical and Matrix Approach with A. Ghali. topic. B Obb29Y9 0552493 2T3 H Over the past 50 years, Neville has written eight books and over 220 research and technical papers. In the last four years, he has writt

19、en 20 papers published by AC1 and FULEM. It is arguable that his output is not large for 50 years of work. This would be true, had he done nothing but “concreting;” however, Neville spent, or wasted, nine years being Principal (President) of the University of Dundee, Scotland, and four years being F

20、oundation Dean of Engineering and Foundation Dean of Graduate Studies as part of establishing the University of Calgary, Canada. All this is not the full explanation; he has been a skier from the age of five, with his latest season in 2000. Whether this was his swan song will not be known until the

21、next snow falls. If you add all the hours spent on the ski slopes, they would suffice to write another book or two. By the way, his skiing was not entirely divorced from the University. At Calgary, he insisted on graduate students accompanying him on “faculty ski days.” Some of them, from hot countr

22、ies, were apprehensive about exposure to snow, but felt it wise to humor the Dean! During the last 12 years, Neville has been working full-time as a consultant and expert in problems and disputes concerning concrete structures of all kinds including highways, nuclear power stations, suspension bridg

23、es, and dams. Adam Neville has received wide recognition: three honorary doctorates, several honorary fellowships, the title of commander of the order of the British Empire for his contribution to science and technology, numerous prizes and awards, and honorary membership of ACI. It is my pleasure t

24、o be the editor ofthis book dedicated to Adam Neville. Akthem Al-Manaseer Editor IV Obb2949 0552494 L3T m FOREWORD I am delighted to be honored by the publication of the Adam Neville Symposium: Creep and Shrinkage-Structural Design Effects as a Special Publication of the American Concrete Institute.

25、 This Special Publication No. 194 reminds me that I wrote one of the very early Special Publications: Monograph No. 6, titled Hardened Concrete: Physical and Mechanical Aspects, now of course well forgotten. I deeply appreciate the eponymous symposium and this book on creep, especially as I have a l

26、ong connection with the creep of concrete and with AC1 Committee 209 on Creep, which I was chairman of in the early 1960s. Later, I organized and edited two volumes of a Bibliography of Creep and Shrinkage published by ACI. Even at that time, there were several hundreds of papers on those topics. Th

27、e output of papers on creep since then has been prodigious, and much useful information has been obtained. The understanding of the phenomena involved has greatly improved, but we have not yet reached the stage of establishing an unchallenged mechanism of creep, either basic or drying. A large volum

28、e of information on the parameters involved and on factors influencing creep of concrete has been built up. This volume is the latest contribution, but I am sure not the last. The stumbling block to progress has been the attempts to produce a single expression to predict creep and another single exp

29、ression to predict shrinkage. These attempts have not proved easy; indeed, in my opinion, they are not practicable. What has happened instead is a split into groups of researchers, each group believing that it possesses the “truth” about the creep and shrinkage expressions. And yet, it seems that no

30、ne of the expressions has a universal validity as tested by the available data bank. I should add that some of the data are far from recent and they refer to concrete less complex in composition and in the range of materials than is the case today, especially in creep-sensitive structures. In my vie

31、w, such a search for a single expression capable of predicting creep at all ages as a function of a number of parameters is unrealistic. Let me explain the rationale of this assertion. We all have a great interest in being able to predict the compressive strength of concrete, say at 28 days, as a fu

32、nction of various parameters so that we could say: with previously untried materials to be used to make concrete, we can achieve a desired compressive strength and a particular workability by using certain mixture proportions. The fact is that we cannot do so and we must, to a greater or lesser exte

33、nt, resort to experimental procedures and testing. We have lived with this situation quite comfortably and we continue to do so. Admittedly, the necessary strength tests take, at most, 28 days: With respect to creep, however, the necessary long-term testing is often not practical. This is why we sea

34、rch for an expression to fit all combinations of intrinsic and extrinsic factors influencing creep. Over a broad range of possible mixture ingredients and proportions, as well as exposure conditions, every expression that has been proposed has wide confidence limits; to know that the “true” value of

35、 creep has a 95% probability of being within 25% or even more, is not very useful. I believe that we must learn to live with this situation, at least for quite a long time to come. My question is this: Is this situation so bad? The observation is not a criticism of those who attempt to develop the c

36、reep and shrinkage expressions, but rather a critique of their unduly focused efforts. I have to confess that I am somewhat bemused by these continuing efforts, each on an individual track, but the tracks are not convergent. Are these efforts a search for V a31 0bb2749 0552495 076 the holy grail? Ar

37、e they a determined effort to help the designers? Or are they, at least some of them, an ego trip to show oneself right? There is a story that bears upon the search for a single creep prediction expression. Imagine a room painted black, with people in it all dressed in black, and a black cat in it.

38、They are trying to catch the cat; that is philosophy. Imagine the same black room, people, and cat. Every now and again, someone calls out “Ive got it!”; that is religion. Again, imagine a black room, with people dressed in black, and every now and again someone calls out “Ive got it!”, but there is

39、 no cat. That is the search for the creep expression. Much effort has gone into a “reconciliation” of the opposing views. This is not new. Approximately 20 years ago, together with the late Bob Philleo, I was a “conciliator” in an attempt to find common ground between the then propounded expressions

40、. We failed abysmally. Today, we are not much further. The difference is that in the present-day situation it is not a failure but a realistic acknowledgment of the inherently intractable material, concrete, as far as creep and, to a large extent, also shrinkage, are concerned. After all, we are dea

41、ling with a composite material consisting both of manufactured and of natural materials, partly processed in a semi-industrial manner. So, we should accept that this is the reality of “concrete life.” For most concrete purposes, this is a tolerable situation. For complex, sensitive, and special stru

42、ctures, some experimental work is necessary. Because these structures are rarely built in a great hurry, an input is practicable. Now let me briefly turn to the papers in this volume. As a contribution to knowledge, they are highly valuable and we should be grateful to their authors for writing them

43、. As this is “my” symposium volume, I am especially grateful. It is not practicable to comment on all the papers in the present volume; on the other hand, it would be invidious to select only some for comment. There are, however, three authors I should like to mention: John Gardner, because some 40

44、years ago he was my undergraduate student; Jeff Brooks, because he was my Ph.D. student; and Walter Dilger, because he was my post doctorate fellow. They all now are very senior academics. Overall, this volume contains 12 papers written by authors from seven countries: Belgium, Canada, France, Italy

45、, Japan, the United Kingdom, and the United States. The topics include: factors in creep and shrinkage, such as admixtures and various cementitious materials, temperature, and humidity; special consideration of high- performance concrete; kinetics approach to creep and shrinkage; creep and shrinkage

46、 models; testing and field verification of laboratory tests; and also, very importantly, structural effects of creep and shrinkage in reinforced and prestressed concrete, their analysis, and design procedures. We should also acknowledge the contribution of AC1 Committee 209 over many years to the st

47、udy of creep and shnnkage. A committee functions well only if led by an able chairman. For the last few years, this function has been performed by Akthem Al-Manaseer. I have an almost grand-parental relation with him as I was the Ph.D. supervisor of his post-doctoral supervisor. It is fitting to rec

48、ognize Akthems hard work both inside the Committee and in the ensuing preparation of this volume, the Adam Neville Symposium. For this we should all, and especially I, thank him. Adam Neville VI = Ob62949 0552496 TO2 E CONTENTS CREEP AND SHRINKAGE PREDICTION MODEL FOR ANALYSIS AND DESIGN 1 OF CONCRE

49、TE STRUCTURES: MODEL B3 by 2. P. BaZant and S. Baweja CREEP AND SHRINKAGE PREDICTION MODEL FOR ANALYSIS AND DESIGN OF CONCRETE STRUCTURES: MODEL B3-SHORT FORM 85 by Z. P. BaZant and S. Baweja DESIGN PROVISIONS FOR SHRINKAGE AND CREEP OF CONCRETE by N. J. Gardner 101 CREEP AND SHRINKAGE OF CONCRETE - KINETICS APPROACH by F. Ulm, F. Le Maou, and C. Boulay 135 SIMPLIFIED METHOD TO ACCOUNT FOR EFFECTS OF CREEP AND SHRINKAGE IN STRUCTURAL ANALYSIS by D. J. Carreira, M. Daye, and L. R. Greening 155 CREEP ANALYSIS OF STRUCTURES WITH VARIABLE STATISTICAL SCHEME-UNIFIED APPROACH by M. A.