Part 1 Memorials: Robert L'Hermite and his legacy, M.Fickelson the impact of Robert L'Hermite on the evolution of creep and shrinkage theory, Z.P.Bazant a tribute to Douglas McHenry, B.Bresler Hubert Rusch and his legacy, H.Hilsdorf. Part 2 State-of-the-art in mathematical modelling of creep and shrinkage in concrete: physical mechanisms and their mathematical description, J.F.Young et al material models for structural creep analysis, Z.P.Bazant et al creep and shrinkage analysis of structures, O.Buyukozturk et al finite element analysis of creep and shrinkage, C.A.Anderson et al probabilistic models, T.Tsubaki et al conclusions for structural analysis and for formulation of standard design recommendations. Part 3 Summaries of discussions from the symposium: physical mechanisms and their mathematical description, U.Schneider material models, P.E.Roelfstra structural analysis, V.Kristek finite element analysis, L.Cedolin uncertainty of creep and shrinkage predictions, S.G.Reid current research in material modelling, J.W.Dougill current research in structural analysis, B.Espion. Appendices: list of lectures and papers presented at the symposium list of participants.

Mathematical modeling of creep and shrinkage of concrete

I. – Theory of Creep and Shrinkage in Concrete Structures: A Précis of Recent Developments

The constitutive equation for creep, shrinkage and thermal expansion, which reflects correctly the effect of variable humidity and temperature, including the effect of size, shape and stress distribution, is derived. Cement paste and concrete are treated as a multi-phase composite material, in which both the static and thermodynamic conditions of equilibrium must be considered.

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Constitutive equation for concrete creep and shrinkage based on thermodynamics of multiphase systems

Time-dependent behaviour of expansive concrete-filled steel tubular columns

In order to design reliable concrete structures, prediction of long term behaviour of concrete is important by considering a coupling between creep and damage. An experimental investigation on the fracture properties of concrete beams submitted to creep bending tests with high levels of sustained load is reported. The influence of creep on the residual capacity and the fracture energy of concrete is studied. The progression of fracture is followed by the measurement of the crack mouth opening displacement during a three-point bending test. The sustained loading seems to increase the flexural strength of concrete, probably because of the consolidation of the hardened cement paste. The acoustic emission (AE) technique is used to perform the characterization of the influence of creep on the crack development. Results give wealth information on the fracture process zone (FPZ) and the propagation of the crack. A decrease in the amplitude distribution of AE hits is observed in the post-peak region for creep specimens. The width of the FPZ also decreases in this later indicating that the material has a more brittle behaviour which may be due to the development of microcracking under creep and the prestressing of the upper zone of the beam.

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A. M. Freudenthal

Papers

Creep and Creep Recovery of Concrete under High Compressive Stress