Nonlinear finite element modeling of reinforced masonry shear walls for bidirectional loading response

The objective of this paper is to analytically establish the effects of bidirectional loading on the response of reinforced masonry shear walls. To accomplish this, an efficient nonlinear 3D finite element modeling approach was used and proved capable of simulating the capacity (within 10%), failure modes and hysteretic response of both partially-grouted (PG) and fully-grouted (FG) masonry shear walls. This modeling approach was also validated for the prediction of out-of-plane response, and then used to examine the influence of bi-directional loading through a series of parametric studies with out-of-plane drift, wall aspect ratio and vertical stress as variables. Results from this study indicate that out-of-plane drifts corresponding to the collapse prevention limit state reduce the in-plane capacity of PG walls by more than 20%. Further, this study indicates that the sensitivity to out-of-plane drift is increased as the aspect ratio increases and as the vertical stress decreases. Although the capacity of PG walls is influenced by out-of-plane drifts, their hysteretic responses, and in particular, energy dissipation capacities as well as their ductility remain nearly unchanged. As a result, the seismic response of PG masonry walls is likely nominally affected by bi-directional ground motions.