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Comportement du béton sous fort confinement : Étude en compression et en extension triaxiales à l'échelle mésoscopique

Abstract : This Ph.D. thesis aims at characterising and modeling the mechanical behaviour of concrete under high confinement at the mesoscopic scale. This scale corresponds to that of the large aggregates and the cementitious matrix. The more general scope of this study is the understanding of concrete behaviour under dynamic loading. A dynamic impact can generate mean pressures around 1GPa. But the characterisation of a material response, in an homogeneous state of stress, can only be achieved through quasi-static tests. The experimentations led in 3S-R Laboratory have underlined the importance of the aggregates in the triaxial response of concrete. Modeling concrete at the mesoscopic level, as a composite of an aggregates phase and a mortar phase, permits a representation of the aggregates effect. An experimental study of the behaviour of mortar phase is performed. Usual tests and hydrostatic and triaxial high confinement tests are realised. The parameters of a constitutive model that couples plasticity with a damage law are identified from these tests. This model is able to reproduce the nonlinear compaction of mortar, the damage behaviour under uniaxial tension or compression, and plasticity under high confinement. The biphasic model uses the finite element method with a cubic and regular mesh. A Monte-Carlo method is used to place quasi-spherical aggregates that respect the given granulometry of a reference concrete. Each element is identified by belonging either to the mortar or to the aggregate phase. Numerical simulations are compared with the experimental tests on this concrete. The parameters for these simulations are only identified on the mortar. The simulations reproduce the different phases observed in hydrostatic compression. The evolution of axial moduli under growing confinement is shown, as is the good reproduction of the limit-states experimentally observed under high confinement. The fracture aspect of numerical simulations is comparable with that of experimental tests. The triaxial extension loading shows the limits of this numerical model.
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https://tel.archives-ouvertes.fr/tel-00365786
Contributor : Fabrice Dupray <>
Submitted on : Monday, July 20, 2009 - 4:33:05 PM
Last modification on : Thursday, November 19, 2020 - 3:54:37 PM
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  • HAL Id : tel-00365786, version 2

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CNRS | 3S-R | UGA

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Fabrice Dupray. Comportement du béton sous fort confinement : Étude en compression et en extension triaxiales à l'échelle mésoscopique. Sciences de l'ingénieur [physics]. Université Joseph-Fourier - Grenoble I, 2008. Français. ⟨tel-00365786v2⟩

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