Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.