MODELISATION DES DEFORMATIONS DIFFEREES DU BETON SOUS SOLLICITATIONS BIAXIALES. APPLICATION AUX ENCEINTES DE CONFINEMENT DE BATIMENTS REACTEURS DES CENTRALES NUCLEAIRES

Abstract : The prediction of delayed strains is of crucial importance for durability and long-term serviceability of concrete structures (bridges, containment vessels of nuclear power plants, etc.). Indeed, creep and shrinkage cause cracking, losses of pre-stress and redistribution of stresses, and also, rarely, the ruin of the structure.

The objective of this work is to develop numerical tools, able to predict the long-term behavior of concrete structures. Thus, a new hydro mechanical model is developed, including the description of drying, shrinkage, creep and cracking phenomena for concrete as a non-saturated porous medium. The modeling of drying shrinkage is based on an unified approach of creep and shrinkage. Basic and drying creep models are based on relevant chemo-physical mechanisms, which occur at different scales of the cement paste. The basic creep is explicitly related to the micro-diffusion of the adsorbed water between interhydrates and intrahydrates and the capillary pores, and the sliding of the C-S-H gel at the nano-porosity level. The drying creep is induced by the micro-diffusion of the adsorbed water at different scales of the porosity, under the simultaneous effects of drying and mechanical loadings. Drying shrinkage is, therefore, assumed to result from the elastic and delayed response of the solid skeleton, submitted to both capillary and disjoining pressures. Furthermore, the cracking behavior of concrete is described by an orthotropic elastoplastic damage model. The coupling between all these phenomena is performed by using effective stresses which account for both external applied stresses and pore pressures.

This model has been incorporated into a finite element code. The analysis of the long-term behavior is also performed on concrete specimens and prestressed concrete structures submitted to simultaneous drying and mechanical loadings.
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https://tel.archives-ouvertes.fr/tel-00006945
Contributor : Farid Benboudjema <>
Submitted on : Wednesday, September 22, 2004 - 3:47:05 PM
Last modification on : Wednesday, April 17, 2019 - 1:19:10 AM
Long-term archiving on : Friday, April 2, 2010 - 8:50:49 PM

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Farid Benboudjema. MODELISATION DES DEFORMATIONS DIFFEREES DU BETON SOUS SOLLICITATIONS BIAXIALES. APPLICATION AUX ENCEINTES DE CONFINEMENT DE BATIMENTS REACTEURS DES CENTRALES NUCLEAIRES. Matériaux. Université de Marne la Vallée, 2002. Français. ⟨tel-00006945⟩

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