Jean‐François Georgin

Nuclear cooling tower submitted to shrinkage; behaviour under weight and wind

A numerical formulation to analyse nuclear cooling tower submitted to creep and shrinkage of concrete is presented in this paper. Both humidity effects and non-linear mechanical behaviour of the constitutive materials are taken into account. Moisture migration is described using a single diffusion equation in which the relative humidity is the driving force and delayed strains are obtained in a phenomenological way. To capture the time-dependent behaviour, an extension of a continuum plasticity model which incorporates viscous behaviour, has been developed and its main parameters are obtained from experimental results. The effects produced by internal stresses that result from time-dependent deformations are finally presented for nuclear towel under services loading.

Fluage tertiaire du béton en traction: Modélisation d'éprouvettes entaillées sous chargement de traction maintenu élevé

ABSTRACT During aging of concrete, the observation of cracking growth under loads corresponds to a recent pathology of the civil engineering works (bridge, dam, confinement building). An interaction mechanism between creep strains and damage appears under high level stresses and creates irreversible changes. Both strength and tertiary creep tests on notched specimens under direct tensile stresses are performed until failure by Carpinteri and al. (1997) and put in a prominent manner this interaction. This research is based on the knowledge of the creep process in its tertiary phase. It allows proposing a numerical model, which can reproduce the interaction mechanism considering the rate effect of loading.

Modélisation du comportement mécanique du béton par une approche plastique endommageable

ABSTRACT This paper deals with an elastic-plastic model used to describe the concrete behavior. Coupling with damage theory can improve the phenomenological modeling. The aim of this paper is to put in a prominent manner the hypotheses and theoretical aspects which lead to the development of this approach.

Un modèle numérique pour l'étude du comportement hydro-mécanique du béton: Application sur structure en béton armé soumise au fluage de dessiccation

ABSTRACT A numerical formulation to analyse creep and shrinkage of concrete is presented in this paper. Both humidity effects and non-linear mechanical behaviour of the constitutive materials are taken into account. Moisture migration is described using a single diffusion equation in which the relative humidity is the driving force and delayed strains are obtained in a phenomenological way. To capture the time-dependent behaviour, an extension of a continuum plasticity model which incorporates viscous behaviour, has been developed and its main parameters are obtained from experimental results. The effects produced by internal stresses that result from time dependent deformations are finally presented for a beam subjected to a classic four-point bending test and numerical results show close agreement with experimental data.