Modelling of the out-of-plane behaviour of unreinforced masonry panels using the Discrete Macro-Element Method (DMEM)

Existing unreinforced masonry (URM) buildings, including historical and monumental structures, represent an important architectural and cultural heritage for several countries worldwide. The response of URM, subjected to earthquake excitations, is strongly governed by the out-of-plane (OOP) response of masonry walls, which can lead to local failure mechanisms, even at low levels of seismic loading. The OOP failure conditions are mainly controlled by the geometry of the structure and the masonry quality. Different strategies are used for modelling the OOP response of URM structures including limit analysis and nonlinear FEM. A further recently proposed strategy is based on the discrete macro-element method (DMEM) which allows the simulation of the in-plane and the OOP response of masonry walls with a reduced computational cost compared to the other numerical strategies. In this paper, the DMEM is applied to simulate a masonry wall rocking experimental campaign for which other numerical strategies have already been applied. The dissipation effects, related to the rocking motion and the repetitive impacts, are taken into account according to an equivalent viscous damping approach. Furthermore, the role of masonry deformability is investigated by comparing the results obtained by the DMEM model, for different value of masonry elastic modulus, with those obtained by typical rigid-block based models. The results clearly demonstrate that the DMEM can be efficiently adopted to accurately predict the dynamic response of monumental structures.