EARTHQUAKE RESPONSE OF BASE ISOLATED LIQUID STORAGE TANK TO BI-DIRECTIONAL GROUND MOTION

摘要

Seismic response of the liquid storage tanks isolated by the lead-rubber bearings is investigated for bi-directional earthquake excitations (i.e. two horizontal components). The biaxial force deformation behaviour of isolation system is modelled by coupled non-linear differential equations as suggested by Park et al. The continuous liquid mass of the tank is modelled as lumped mass, which are known as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses has been worked out depending upon the properties of the tank wall and liquid mass. The seismic response of two types of the isolated tanks, slender and broad tanks, is investigated under real earthquake ground motion. In order to investigate interaction of seismic response of isolated tank, bi-directional responses are compared with corresponding unidirectional response. Also, in order to measure effectiveness of the isolated system to reduce seismic forces the response of isolated tank, bi-directional and unidirectional, is compared with the corresponding response of the tank without isolation system.