Vector-Valued Intensity Measures for Seismic Risk Assessment of Base-Isolated Liquid Storage Tanks

The present study proposes vector-valued intensity measures (IMs), consisting of two IM parameters, for improved and efficient seismic risk assessment of liquid storage tanks base isolated with laminated rubber bearing (LRB) and lead rubber bearing or New Zealand base-isolation system (NZ system). To assess the seismic risk of the base-isolated liquid storage tanks, their seismic fragility was obtained using stripe analysis. The joint hazard of the selected IMs was obtained using vector-valued probabilistic seismic hazard analysis. It is shown that the vector-valued intensity measure consisting of peak ground acceleration (PGA) and spectral acceleration (Sa) at the isolation period (Tb) is efficient for predicting the peak base shear demand in the liquid storage tanks base isolated with LRB. Similarly, the vector-valued intensity measure consisting of PGA and peak ground velocity (PGV) is efficient for predicting the peak base shear in the liquid storage tanks base isolated with the NZ system. This study also presents parametric investigations on the effect of thicknesses of the tank wall (tw) and the slenderness ratio (S) of the tank on the seismic risk of the base-isolated liquid storage tanks.