Seismic collision potential of adjacent base-isolated buildings with corridor bridges subjected to bidirectional near-fault pulse-like ground motions

Adjacent base-isolated buildings with corridor bridges have a large seismic displacement demand in their isolation layer, and therefore are prone to collision. Moreover, seismic wave incidence angles may have a great impact on their seismic collision response, especially for near-fault ground motions that may exhibit strong directionality dependence. This paper studies the impact of seismic wave incidence angle and near-fault pulse effect on seismic collision potential of adjacent buildings connected by corridor bridges, retrofitted with base isolation. Two adjacent-building systems are established in OpenSees to facilitate analyses. One is a base-isolated (BI) building system adopted as the baseline model, each building of which consists of lead-rubber bearings (LRB) and ordinary-rubber bearings (LNR). The other one is a base-isolation-with-damper (BID) system, where two additional groups of viscous dampers were added to the isolation layers of BI system. The first group of dampers is used to connect the buildings in order to reduce their out-of-phase motion. The second group of dampers is placed at the base of individual buildings to dissipate seismic energy. The effectiveness of using the dampers of the BID results against the BI baselines was compared. A collision potential index D was proposed to quantify the collision potential of the adjacent base-isolated buildings. The research shows that, the seismic wave incidence angle has a great influence on the building collision potential, which does not necessarily be greatest in the maximum pulse direction. Using dampers may not be useful for reducing building deformation demands, but can effectively coordinate the asynchronous movement of adjacent buildings, reducing the potential of seismic collision. Finally, the Pseudo-Spectral Acceleration (PSA) based on the isolation periods of the buildings was shown to correlate well with the index D, which can be used as the pair of seismic Intensity Measure (IM) and Engineering Demand Parameter (EDP) to describe the collision potential between adjacent base-isolated buildings with corridor bridges.