An innovative approach for the finite element modelling of masonry cracking

The performance of masonry structures under seismic conditions is strongly influenced by cracking phenomena that have to be taken into account to obtain a reliable evaluation of mechanical resources. An innovative finite element procedure is presented to simulate initiation and propagation of in-plane tensile crack in masonry material. The material is studied at the macro-level and modelled as a homogenous continuum by means of triangular shell elements. The cracks are considered as localized inelastic deformations in the frame of the classical theory of plasticity. Control of tensile stress is formulated and implemented along possible cracking lines, corresponding to the mesh edges, in terms of generalized forces at the nodes. When the limit tension is reached at one node and the crack starts to open, the activated inelastic constitutive law is taken as a single-branch softening curve. A Parametric Linear Complementarity Problem is solved to evaluate the cracking evolution of the structure until collapse. Some numerical examples are presented to validate the formulation.