A damage model for masonry structures

In this paper a brittle damage model for masonry structures characterized by a unit cell composed of mortar, blocks and a finite number of fractures is proposed. Initially, a micromechanically consistent binary representation of the damage variable is proposed for regular heterogeneous media, and a discrete damage kinetic law is developed. Then, a typical masonry material is considered and a specific damage model is derived from the previous one by employing the classical cohesive Coulomb failure criterion and by taking into account the specific microstructure of the masonry. This damage model is used to formulate the nonlinear quasistatic problem of masonry structures subject to assigned loading paths. Then, a numerical procedure based on the finite element method is implemented in a computer code. Finally, some applications are developed to analyze the nonlinear behavior of simple masonry structures and to show the capability of the proposed damage model to capture the differences of behavior by varying the microstructure and the physical properties of the masonry.