FEM analysis of orthotropic masonry walls via localized damage models

Abstract

In finite element analysis of masonry structures, continuum damage models are generally combined with a smeared description of damage. This common approach however, fails to provide a realistic simulation of damage and only affords general information on expected damage levels. Moreover, spurious mesh-size and mesh-bias dependence emerges from the discrete problem. In order to overcome these drawbacks, this work proposes a smeared model modified in such a way that it can reproduce localized individual (discrete) cracks. This is achieved by means of a crack tracking algorithm, which enforces the crack to develop along a single row of finite elements. In addition, the material orthotropic behaviour is simulated making use of the concept of mapped stress and strain tensors from the anisotropic real space to a scaled isotropic one. This original methodology establishes a one-to-one mapping relationship between the behaviour of the anisotropic material and that of a corresponding scaled isotropic one. In this way, the problem is solved in scaled space and the results are mapped back onto the anisotropic field, with consequent advantages from the computational point of view. The validity of the model is demonstrated through the comparison between the numerical results and the experimental evidence observed on an in-plane loaded masonry wall.