Contribution to the mechanical and numerical modelling of masonry buildings

V. Acary, PhD thesis, University Aix-Marseille II, 2001


Equilibrium under gravity load - Reactions (magnification= 30000)	Velocity and stresses during shear wave excitation (magnification= 200)]

Equilibrium under gravity load - Stresses (magnification= 30000)	Stresses at equilibrium after shear wave damage (magnification= 200)]

Abstract :

From a mechanical point of view, masonry appears as a composite quasi-brittle geomaterial, characterized by the coexistence of three scales of studies (macroscopic, mesoscopic and microscopic) and two closely related mechanical behaviors: the brittle damage and the non associated plasticity. After an extended review of various existing modelling (phenomenological approach, micromechanical approach and multiscale analysis), it is concluded that two major obstacles are pointed out : the influence of bond on the macroscopic mechanical response and the strain localisation. In this work, a discrete micromechanical modelling in a non-smooth dynamical framework is proposed. Masonry material is considered as a divided medium composed of a collection of deformable bodies in interaction through non-smooth interface laws. The basic model for dry joints, based on unilateral contact and dry friction, is enhanced for mortar joints by cohesive zone models, with brittle failure or continuous damage. The computational framework is based on the Non-Smooth Contact Dynamics method, designed to numerically integrate a non-smooth dynamical evolution with unilateral contact and dry friction. Finite element methods are used for non-linear behavior of each body and are modified to take into account the discrete character of the considered structure. Non-smooth interface laws are solved by means of iterative solvers dedicated to large scale complementarity problems. Finally, an interdisciplinary work has been made with architects and building archaeologists, in order to study monumental buildings in their natural context by means of numerical stereophotogrammetry.

Key-words :

Non-smooth dynamics, unilateral contact, Coulomb friction, Cohesive zone models, divided materials, quasi-brittle geomaterials, masonry, monumental buildings.

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