A multi-level interface model for damaged masonry
Résumé
The aim of the present work is to propose a new micromechanical method in the context of the deductive approach used to derive the interface models. This model, based on a previous study proposed by A. Rekik and F. Lebon [1, 2], is used to reproduce the damage in masonry by combining structural analysis and homogenization methods. The focal point of this method is assuming the existence of a third material, called interphase, which is a mixture of the two principal constituents of masonry, brick and mortar, and that is the interface between them. This new element presents a low thickness, a low stiffness and a given damage ratio. The mechanical problem of masonry, initially a 3D problem, is solved numerically as a 2D problem using finite element methods and considering three materials: brick, mortar and the defined interface material. The properties of the last material are obtained using the three following steps: (I) an exact homogenisation of a brick/mortar laminates defining a first homogeneous equivalent medium named HEM-1. (II) One assumes that HEM-1 is damaged and applies the Welemane-Goidescu [3-5] model to evaluate the global behaviour of the damaged HEM-1 defining thus a second equivalent homogeneous medium noted HEM-2. (III) Asymptotic analysis is used to model HEM-2 as an interface or a joint. The properties of this joint are deduced from those of the HEM-2 material as proposed in former papers [6-9]. Particularly, through the second homogenization is taken into ac-count for variable oriented family of microcracks and simultaneously for opening-closure effects (unilateral behaviour). Numerically this interface is modelled with connector finite elements. Numerical results are compared to experimental ones available in the literature.
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