Seismic performance of cylindrical ground sup-ported liquid storage tanks with and without base isolation system is investigated. Further, the effect of soil–structure interaction is evaluated on the seismic performance of ground supported tanks. The tank structure is considered isolated with lead rubber bearing which follows a bilinear hysteretic force–deformation behavior under lateral loading. Herein, two different geometries (broad and slender)of fixed base and base isolated ground supported tank s are analyzed, and corresponding seismic fragility curves are developed for different base conditions (without and with soil–structure interaction, considering different soil types).The study shows that the soil–structure interaction significantly affects the seismic performance of fixed base and base isolated tanks, and in certain cases, neglecting its effect can underestimate the seismic fragility of ground supported tank. Further, the tank structure provided with base isolation system may not follow the trend of response shown by the system without isolation under different soil conditions. The general perception of response reduction with smaller soil stiffness, in order to neglect the soil–structure interaction effect s, may not always hold good. The response of base isolated tank is greatly affected by the soil type over the possible range of seismic intensities.

Base Isolation; Earthquake Response; Lead Rubber Bearing; Liquid Storage Tank; Seismic Fragility; Soil–Structure Interaction.