Sensitivity of drift capacities of URM walls to cumulative damage demands and implications on loading protocols for quasi-static cyclic tests
Displacement-based seismic design and assessment procedures require as key input parameter estimates of displacement capacities of the critical elements. The displacement capacities of unreinforced masonry (URM) walls are typically determined by means of quasi-static cyclic tests. This paper shows that for URM walls failing in shear the number of applied cycles in quasi-static cyclic tests influences the drift capacities obtained from these tests. It is therefore important that loading protocols are used that reflect the expected cumulative damage demand. The latter will depend on the structural properties and the seismicity of the region. Existing loading protocols for quasi-static cyclic testing were derived to reflect the cumulative cyclic demands in regions of high seismicity and where derived for structural systems other than masonry buildings. For regions of moderate seismicity, these protocols are likely to underestimate the actual drift capacities. Based on statistical analysis of the displacement response of SDOF systems representative for URM buildings, the paper proposes new loading protocols for quasi-static cyclic tests on URM walls.