Nonlinear vibration control assessment of base-isolated liquid storage tanks under near-fault pulse-like ground motions

Abstract

Seismic isolation is a popular technique for passive control of the seismic response of liquid storage tanks. While isolated tanks respond appropriately to far-field earthquake excitations, near-field ground motions can still present difficulties, particularly when forward-directivity effects are present. This study examined the seismic behavior of seven liquid storage tanks that were isolated using elastomeric bearings and exposed to 378 pulse-like ground motions. These ground motions included symmetric and anti-symmetric velocity pulse shapes derived from equivalent analytical equations of near-field earthquakes. The bearing’s shear force–deformation behavior is represented by a bi-linear model using the nonlinear first-order differential Bouc–Wen function. The tank’s liquid mass is represented as lumped masses called convective, impulsive, and rigid masses. The modified Gabor wavelet transform is used to produce artificial pulse-like seismic excitations. The study found that the seismic reaction of isolated and fixed tanks, along with the effectiveness of the isolation system in reducing this response, is influenced by input acceleration parameters such as pulse shape and period. An 80% reduction in base shear was seen for pulses that offer optimal performance in reducing seismic response. Also, by altering the isolator’s system parameters, it is feasible to enhance its performance and achieve a 30% reduction in the base shear caused by pulses that negatively impact seismic response.