Analysis of seismic response of a large-scale isolated LNG tank considering dynamic soil-pile interaction

Seismic safety is a critical issue for liquefied natural gas (LNG) tanks. It is essential to investigate the effect of the isolation system on the seismic response of LNG tanks, considering dynamic soil-pile interaction, especially for tanks located in the deep soil site. This study aims to quantitatively evaluate the effects of isolation system (e.g., lead-core rubber bearings) on various aspects of a large LNG tank located on a deep soil site under horizontal bidirectional seismic action. Specifically, the evaluation includes outer tank acceleration, inner tank base shear, overturning moment, and pile force distribution. The findings demonstrate that the isolation system can effectively minimize the transfer of inertial interaction from the superstructure to the pile foundation, optimize the internal force distribution within the pile foundation, mitigate the pile group effect, and enhance the safety margin of the structure. Moreover, the isolation system can effectively suppress the transmission of seismic energy in medium and high frequencies, but amplify it in the low-frequency domain. Consequently, it is recommended that it is needed to avoid the site's natural frequency in the design of seismic isolation bearings for LNG tanks.