A 2D Cosserat finite element based on a damage-plastic model for brittle materials

• A 2D damage-plastic model for Cosserat brittle materials is formulated.
• Two different damage mechanisms in tension and compression are modeled.
• The mechanical response of heterogeneous materials with non regular texture is reproduced.
• The pathological mesh-dependency related to strain softening is overcome.
• The global response curves and the damaging mechanisms of walls under lateral loading is described.

A 2D2D Cosserat model with a damage-plastic isotropic constitutive law for brittle-like materials is presented. Different damaging mechanisms in tension and compression are considered. The plastic flow is described by introducing a suitable yield function and evolution laws in terms of effective stresses. Small strain and displacement assumptions hold. A 4-node finite element is formulated with three degrees-of-freedom for each node and a predictor–corrector procedure is used to solve the damage-plastic evolutionary problem. The lateral response of walls under monotonic and cyclic horizontal actions is analyzed and a satisfactory description of the global response curves and damaging mechanisms is obtained.