Seismic Assessment of Base-Isolated Structure Under a Sequence of Near-Fault Earthquake Records

This paper investigates the performance and efficacy of Quintuple Friction Pendulum (QTFP) isolators under a sequence of near-fault foreshock, mainshock and aftershock earthquake events. The QTFP isolator is an advanced base isolation device utilized in Reinforced Concrete (RC) structures to alleviate damage from severe seismic activity. Despite its proven ability to restrict structural responses and meet particular performance goals under severe seismic excitation, comprehensive analyses of QTFP isolators performance under sequential earthquakes are scarce. This research employs finite element analysis to explore the seismic behavior of RC structures equipped with QTFP isolators during such sequences. It also assesses the effectiveness of QTFP isolators by evaluating the seismic behavior of base-isolated RC structures subjected to sequence earthquakes. In general, the sequence of foreshock, mainshock and aftershock earthquake events critically impacts the structural response, with the foreshock producing the highest base shear, inter-story drift and acceleration responses. Furthermore, the aftershock accounted for the most considerable input, damping, and hysteretic energies. The research offers insights into the hysteresis behavior of the isolators, particularly during the mainshock, where the combination of 2.15 seconds period and 10% damping showcased the most extensive hysteresis loop cycles. This study underscores the significance of QTFP isolators in enhancing the seismic resistance of RC structures, while shedding light on their performance under different earthquake sequences.