A numerical and experimental analysis of unbonded brickwork panels laterally loaded

The recent earthquakes occurred in Italy (Umbria and Marche 1997 and Molise 2002) have shown that the collapse of masonry buildings is mostly due to out-of-plane actions, caused, for instance, by an inadequate interlocking between perpendicular walls. In this paper, a combined numerical-experimental analysis on in-scale unbonded masonry panels out-of-plane loaded is presented. Three different Series (A, B and C) of mortarless walls subjected to in-plane compressive loads and concentrated out-of-plane actions are considered. Series A is restrained at two perpendicular edges and subjected to an eccentric out-of-plane load, whereas Series B and C are constrained at the base and on both vertical edges and are subjected to an eccentric (Series B) or centered (Series C) out-of-plane load. Experimental tests are repeated in presence of three different vertical membrane compressive loads equal to, respectively, 7, 10 and 13 kN. Two different numerical models, relying in an upper bound heterogeneous FE limit analysis and in a FE homogenized limit analysis approach, are employed to have a better insight into the experimentation conducted. The combined numerical-experimental information obtained shows that anisotropic masonry behaviour and vertical compressive loads are key aspects to consider to have a reliable prediction of both collapse loads and failure mechanisms.