Performance limits of base-isolated liquid storage tanks with/without supplemental dampers under near-fault earthquakes

Abstract

In order to ensure the continuity of the production process and avoid health, security, and ecological problems, the protection of the liquid storage tanks (LSTs) in industrial complexes against earthquakes is vital. Although base-isolation is successful in protecting LSTs from the detrimental effects of far-fault earthquakes, it is challenged by large-amplitude and long-period velocity pulses observed in near-fault earthquakes which may cause large isolator and sloshing displacements. Employing supplemental damping in the isolation system may reduce isolator displacements but the improvement in the superstructure response may be limited if not worsened. Thus, determining the performance limits of base-isolated LSTs with/without supplemental damping in terms of both isolation system and superstructure responses through a systematic examination considering different levels of earthquake magnitude and different fault distances is essential. Since the period and the amplitude of the ground velocity pulse is dependent on the earthquake magnitude and the closest fault distance, such an examination will also help reveal the influence of the characteristic properties of near-fault pulses on the responses of these structures. Therefore, here, a benchmark LST with different base-isolation systems with/without supplemental viscous dampers, located at different fault distances are subjected to synthetically generated near-fault earthquake records with different levels of moment magnitudes. Various isolator and viscous damper characteristics are taken into account. Non-linear time history analyses are conducted to obtain isolator displacement, sloshing displacement, and isolation system shear force responses and the performance limits of the benchmark LST with different base-isolation systems with/without supplemental dampers are presented in a comparative manner.