ABSTRACT
Masonry constructions are a significant part of the existing civil, architectural and cultural heritage. The preservation of their structural integrity requires developing efficient and accurate tools to represent their degradation and assess their safety and vulnerability under complex loading. In this paper, a constitutive model, built within the framework of thermodynamics of irreversible processes, describes the nonlinear mechanical response of masonry by introducing couplings in the free energy and the pseudo-dissipation potential of the material. The damage model decomposes the effects of cracks families that behave independently on the compliance tensor. Plastic flow develops independently along with the orthotropic directions of masonry, which allows friction effects to be decoupled. The unilateral effect related to crack closure during alternating loading is also modelled. A coupling between orthotropic elasticity and damage is introduced for the normal components and an additional coupling between damage and internal friction for the shear components. Using this formalism, the contributions to the overall dissipation of each degradation mechanism can be evaluated. Comparisons between experimental and numerical results performed on masonry shear panels under monotonic and cyclic loading are hereby presented. The model is able to satisfactorily describe the experimental outcomes, reproducing the damage distribution, the hysteresis loops and dissipative processes.
