To understand the susceptibility that buildings with flexible diaphragm systems have to earthquakes, their seismic response to tri-axial base motions is assessed. The research centers on a tri-directional analytical study of a two-story half-scale unreinforced masonry (URM) structure. The study investigates the effect of tri-axial base motions on response of the structure. It determines how individual component behavior, such as a pier or floor diaphragm, affects the behavior of the ...