A plastic nonlocal damage model

In the present paper, a plastic nonlocal damage model is proposed for studying the mechanical response of structural elements made of cementitious materials. A new isotropic damage model, which is able to describe the behavior of a wide class of cementitious materials, is presented. A regularization technique, based on the introduction of the damage Laplacian in the damage limit function, is adopted to overcome the analytical and computational problems induced by the softening constitutive law. A Drucker-Prager type of plastic limit function is proposed considering isotropic hardening. A numerical procedure, based on an implicit 'backward-Euler' technique for the time integration of the plastic and damage evolution equations, is presented. To solve each nonlinear step, a predictor-corrector iterative method is developed within the splitting method. In particular, the damage evolution is determined solving a constrained minimization problem of a convex functional. The proposed algorithm is implemented in a finite element code and it is used to study the structural behavior of elements made of masonry materials.