Seismic gap between buildings founded on different soil types experiencing pounding during earthquakes

Several formulas have been suggested in the literature to evaluate the minimum seismic gap that would prevent collisions between adjacent buildings during earthquakes, including those based on the absolute sum of the peak displacements (ABS), square root of the sum of the squares (SRSS), the double difference (DDC) method, Australian code, and approach proposed by Naderpour et al. The aim of the present study is to evaluate the influence of the seismic gap on the behavior of buildings experiencing pounding, as well as verify the accuracy of these five formulas for structures founded on different soil types. Three buildings (4-story, 6-story, and 8-story buildings) were considered and three pounding scenarios were modeled. In the first part of the study, these three pounding scenarios were analyzed by considering three different seismic gaps (1 mm, 1 cm, and 1 m). In the second part, the accuracy of the aforementioned formulas was verified for buildings founded on different soil types (hard rock, rock, very dense soil and soft rock, stiff soil, and soft clay soil). The results indicated that the seismic gap had a significant influence on the response of colliding buildings, including the peak story accelerations and pounding forces. Moreover, increasing the gap did not always lead to a reduction in the effects of pounding, unless it was large enough to eliminate structural collisions during earthquakes. In addition, all five formulas were found to provide poor estimates when considering different soil types. The ABS and the Naderpour et al. formulas were found to always be conservative, but they overestimated the minimum gap that would prevent pounding. Moreover, the DDC and Australian code formulas provided overestimate, accurate, and underestimate results, and the SRSS formula provided both accurate and overestimate results.