Effects of vertical ground motions on the dynamic response of URM structures: Comparative shake‐table tests

This paper discusses the results of an experimental study aimed at evaluating influence vertical ground motion component on seismic performance unreinforced brick-masonry buildings. The research was motivated by post-earthquake observations significant structural damage in vicinity fault, where horizontal and motions are often strong synchronized. Vertical accelerations can fluctuate gravity loads, which control in-plane lateral load capacity masonry piers affect out-of-plane overturning stability thin walls. Such phenomena seem not to be sufficiently explained existing literature, while evidence is undoubtedly missing. Here, potential investigated through a series multidirectional shake-table tests full-scale structures under simulated near-source increasing intensity. experiments comprised three nominally identical building specimens subjected principal alone, combined with one, full three-component motion. buildings included structural/nonstructural elements (e.g., gables, chimneys, parapets) sensitive variations due their low axial loads. Two different sets earthquake records were employed assess effects both tectonic induced seismicity scenarios. Overall, did cause appreciable differences behavior Any strength peak response walls marginal non-systematic. Data from these add substantially our understanding acceleration structures.