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Abstract: Unreinforced masonry (URM) walls show a limited horizontal in‐plane deformation capacity, which can lead to an unfavorable seismic response. To predict this response, the walls' effective stiffness, shear force and drift capacity are required. While mechanics‐based models for the force capacity are well established, such approaches are largely lacking for the effective stiffness and the drift capacity. The mostly empirical code equations for the two latter parameters lead to often unsatisfactory and, in the case of drift capacities, sometimes unconservative predictions when compared to test results. This article summarises recently developed simple closed‐form equations for the effective stiffness, the shear force and the drift capacity. Furthermore, it compares said formulations and currently used code equations to a database of shear compression tests. It shows that the novel models capture the effective stiffness and the drift capacity more accurately than current code equations. The shear force capacity is predicted with a similar reliability, yet using a very simple formulation. [ABSTRACT FROM AUTHOR]

Current design codes provide empirical equations for the drift capacity of unreinforced masonry (URM) walls that are based on results of quasi-static cyclic shear-compression tests. Yet different experimental campaigns have used various approaches of imposing fixed-fixed boundary conditions at the wall top which may affect the test results. This article investigates, by means of numerical simulations, the influence of experimental setups on the force and drift capacities of in-plane loaded URM walls subjected to double-fixed conditions. It is shown that controlling the shear span or the top rotation while keeping the axial force constant leads to very similar results. Controlling the axial elongation at the top of the wall results for walls subjected to a small axial load ratio in an increase and for walls subjected to a large axial load ratio in a decrease in axial load with increasing drift demands. Testing a wall with half the height applying cantilever boundary conditions is not recommended as the stiff loading beam at the wall top changes the failure mode and leads to significantly larger drift capacities. [ABSTRACT FROM AUTHOR]

Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that are subjected to different loading protocols. The study shows that the force capacity is not very sensitive to the loading protocol. The drift capacity of walls failing in shear is, however, rather sensitive to the loading history while the drift capacity of walls failing in flexure is not. The largest difference in drift capacity of up to 100% is observed between monotonic and cyclic loading for shear controlled walls under double-fixed boundary conditions and low axial load ratios. [ABSTRACT FROM AUTHOR]

This article introduces an analytical model to compute the monotonic force-displacement response of in-plane loaded unreinforced brick masonry walls accounting for walls failing in shear or flexure. The masonry wall is modelled as elastic in compression with zero tensile strength using a Timoshenko beam element. Its cross-section properties (moment of inertia and area) are continuously updated to capture the non-linearity that results from flexural and shear cracking. For this purpose, diagonal cracking of shear critical walls is represented by one Critical Diagonal Crack. The ultimate drift capacity of the wall is determined based on an approach evaluating a plastic zone at the wall toe. Validation against results of cyclic full-scale tests of unreinforced masonry walls made with vertically perforated clay units shows that the presented formulation is capable of accurately predicting the effective stiffness, the maximum strength and the ultimate drift capacity of the wall. It outperforms current empirical code equations with regard to stiffness and ultimate drift capacity estimates and yields similar results concerning strength prediction. [ABSTRACT FROM AUTHOR]