Fundamental Research on Creep and Shrinkage of Concrete

ISBN-13: 9789401037181 / Angielski / Miękka / 2011 / 528 str.

F. H. Wittmann

Opis

Today research on creep and shrinkage of concrete is diversified to such a degree that specialists working in different areas sometimes find it difficult to understand one-another. Materials scientists are mainly interested in processes on a microstructural level but they do not necessarily understand the relevance of time dependent deformation in structural design. On the other hand engineers who apply simplified model laws in non-elastic structural analysis are not always in the position to judge the limitations implied in their approach. It is generally realized that further development can be stimulated by a more effective exchange of results and ideas among the different groups involved. In an attempt to bridge this obvious gap in September 1980 there was a Conference organized at Swiss Federal Institute of Technology in Lausanne. The papers presented at this meeting covered the wide range starting with microstructural aspects and mechanisms and including constitutive modelling and structural creep analysis. These contributions together with summaries of two panel discussions are being published in this volume. All serious of the meeting have been introduced by invited lectures. These papers will be published in a special volume "Creep and Moisture Effects in Concrete." This special volume is rather to be a general survey of the different areas covered while the present conference proceedings provide a unique selection of research papers. Nowadays time-dependent deformation of concrete can be taken into consideration realistically by computerized structural analysis.

Spis treści

I. Mechanisms of Creep and Shrinkage.- A model of hardened cement paste for linking shrinkage and creep phenomena.- The use of activation spectrum theory to describe creep in concrete.- Deformation kinetics of concrete.- Shrinkage and swelling of two hydrated alite pastes.- Creep and micro structural changes in concrete.- Isothermal drying shrinkage and wetting swelling of hardened cement paste.- II. Stochastic Nature of Creep and Shrinkage.- Etude expérimentale de la variabilité du retrait du béton/ Experimental study of the variability of shrinkage in concrete.- Variability of creep and shrinkage of concrete.- Creep of concrete — A stochastic quantity.- III. Experimental Techniques and Results.- A contribution to the problem of reversible and irreversible creep of compact structural concretes.- Checking the principle of superposition by testing.- Drying of concrete: Consequences for the evaluation of creep test.- Relaxation tests on very old concrete.- Rheological properties at high temperature of a concrete with a crushed limestone aggregate and blast furnace cement.- Creep effects under transient temperature conditions.- Shrinkage of concrete in extreme climate.- Drying shrinkage of symmetrically reinforced concrete and some estimates of the creep of concrete in tension.- Deformations de sections transversales et de poutres fléchies sous charge soutenue.- Early shrinkage of hardening cement pastes.- IV. Constitutive Relations for Creep and Shrinkage.- Non linear constitutive equations for concrete.- Analyses of shrinkage in concrete.- Comparison of prediction methods for creep coefficients of structural concrete with experimental data.- On the prediction of creep functions for concrete.- V. Observations on Structures.- Creep and shrinkage behaviour of tall buildings and long span bridges.- Analysis of restrained concrete structures for creep and shrinkage.- Experimental Analysis of prestressed concrete bridges.- VI. Structural Creep Analysis.- Prediction of shrinkage stresses and deformations in concrete.- Computerized structural analysis applied to large span bridges.- Numerical analysis of creep and shrinkage on concrete structures.- The influence of thermal creep on the operational behaviour of complex structures.- Viscoelastic stability analysis of shells.- Stresses and displacements of composite and prestressed structures.- Simplified calculation of the relaxation of stress respecting the delayed elasticity.- Shrinkage and load induced curvature of reinforced concrete beams.- Prise en compte du fluage par la méthode des forces.- Comportement d’une structure continue réalisée à l’aide d’éléments préfabriqués.- Déformation des dalles en béton: Méthode bilinéaire pour le calcul des flèches.- Analysis of linear visco-elastic structures subjected to delayed restraints.- General and approximate method for the analysis of linear visco-elastic structures sensitive to second order effects.- Panel Discussion I.- Microstructural Aspects, Mechanisms and Constitutive Modeling.- Panel Discussion II.- Constitutive Modeling and Structural Creep Analysis.