Gilles Pijaudier-Cabot

Failure and scaling properties of a softening interface connected to an elastic block

The damage growth in a softening interface connected to an elastic block is analysed. The elastic block, assumed to be infinite, is modelled as a two-dimensional continuum and the interface is one-dimensional with a constitutive response which follows a scalar damage model. The solution technique is based on the equilibrium of the interfacial forces resulting from the deformation of the elastic block and from the interface constitutive response. The interface failure process is compared to that of a hierarchical model which was obtained analytically (Delaplace et al., 1998). The two are found to be similar, without an internal length scaling the distribution of damage at the inception of macro-cracking. Finally, scale effects on the occurrence of bifurcation and instability are considered. It is shown that bifurcation may occur prior to or after the limit point under displacement control, depending on the elastic block height or stiffness.

Continuum damage modelling and some computational issues

ABSTRACT Continuum damage mechanics is a framework for describing the variations of the elastic properties of a material due to microstructural degradations. This paper presents the application of this theory to the modelling of concrete. Several constitutive relations are devised, including incremental, explicit, and non local damage models. A general framework for damage induced anisotropy is also presented. In the second part of this contribution, computational issues in damage mechanics related to iterative schemes and solution control in non linear computations are considered. The paper concludes with an example of 3D finite element computation of a reinforced concrete beam, as part of a benchmark initiated by Electricité de France.

Endommagement et rupture des bétons dégradés : Etude d'une modélisation simplifiée

ABSTRACT Chemo-mechanical coupled problems are important for assessing the serviceability and the life time of concrete structures. In the development of constitutive relations, it is also necessary to address the problem of failure due to strain softening and damage localisation. An internal length is necessary in order to obtain well-posedness of boundary value problems. In this paper, we present a simplified generic problem for the study of failure due to coupled actions. We exhibit the influence of the internal length of the material and of the kinetics of chemical/physical degradations on the inception of failure.