N°215. 1993. Structural Effects of Time-Dependent Behaviour of Concrete.
| The Comité Euro- International du Béton has always reserved a special attention to the problem of the structural effects of the rheological properties of concrete . The early editions of the CEB recommendations already in corporated a model for the prediction of creep and shrinkage . A decisive step toward a more comprehensive information and guidance on the related structural problems was taken with the publication of the 1978 Model Code, which contained a full appendix on the subject. In 1984 CEB published the Design Manual "Structural Effects of Time dependent Behaviour of Concrete" aimed specifically to widen the scope and facilitate the applicability of these guidelines. lt was a pleasure for me , at thetime , to present the Manual and to commend it to the design profession as an innovative tool for the transformation of the evaluation of creep effects in reinforced and prestressed concrete structures, as well as in composite steel-concrete structures, from rough estimates based on engineering judgement or on inadequate simplifications, into systematic processes founded on rational assumptions and satisfactory models, within the general framework of the reliability checks. The CEB Manual largely contributed in these last years to the dissemination in the engineering community of such a rational approach. After the publication of the new CEB-FIP Model Code 1990 , that incorporates a revised model for the prediction of creep and shrinkage , it has appeared necessary to revise - in this CEB Bulletin -the 1984 CEB Manual , particularly in what concerns the set of design aids in terms of diagrams of the main rheological functions regulating the various structural problems. This Bulletin benefits also of some recent progresses in the elaboration of simplified , and very accurate, approximate rules for the solution of practical problems. lt is therefore a new pleasure for me to present his CEB Bulletin, which will certainly be appreciated by the structural engineers as a useful tool to adapt their design procedures for creep effects to the new guidelines of the CEB-FIP Model Code1 990. Once more Mario Alberto Chiorino, that carried the greatest responsibility for the farmer Manual, has directed the preparation of this Bulletin, and 1 am glad to acknowledge his work and that of his co-worker G . Lacidogna . |
