Seismic evaluation of low-rise reinforced masonry buildings with flexible diaphragms: 1. Seismic and quasi-static testing

This and a companion paper compare the results from shaking-table testing, quasi-static testing, and analytical predictions, to provide a coherent description of the seismic response of low-rise reinforced masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to earthquake ground motions on the Tri-axial Earthquake and Shock Simulator at the United States Army Construction Engineering Research Laboratory, Engineer Research and Development Center. Following the shaking-table tests, diaphragms and top four courses of attached masonry walls are salvaged from the half-scale structures and tested quasi-statically in their own plane. In contrast to what is usually assumed in design, the half-scale specimens do not behave as systems with a single degree of freedom associated with the in-plane response of the shear walls, but rather a system with a dominant degree of freedom associated with the in-plane response of the roof diaphragm. A new index describing the potential for diaphragm damage is introduced, the diaphragm drift ratio. A companion paper, Part II: Analytical Modeling, presents analytical work intended to corroborate and extend results from experimental testing.