A multiscale/multidomain model for the failure analysis of masonry walls. A validation with a combined Fem/Dem approach

An accurate and fast failure simulation for masonry walls is still an active field of research, due to its fundamental role in predicting the overall response of masonry structures under seismic and other extreme natural and manoriginated events. Multiscale models have been successfully exploited for achieving this task, being characterized by high computational efficiency, especially in the presence of strong nonlinearities due to multiple microcrack initiation and propagation. In this paper, a novel multiscale/multidomain approach for nonlinear analysis of masonries is presented, based on a couple-stress homogenization for undamaged regions and an adaptive strategy for triggering the macro-to-micro switching operations. An extended validation of the proposed approach is presented, via suitable comparisons with a micromechanical model, here regarded as a benchmark model, that finely describes the microstructure, based on the combined finite/discrete element method (FEM/DEM). A critical discussion of the obtained numerical results has shown the efficacy of the proposed models as well as their limits of application.