Seismic Responses Analysis Of Pile-Soil-Structure-Isolation System Of Large-scale LNG Tanks

A Low Temperature LNG Storage Tank consists of external wall of prestressed concrete, pile cap, roof, insulation, inner wall of 9% Ni steel and pile foundation. In normal operation condition, the inner wall contains liquid of extremely low temperature, the external wall bears the load transferred from the roof. The external wall also contains divulged liquid and gas, then discharges them in a controllable method.The integrated model of LNG tank was established by Ansys, including pile, soil and upper structure. Three different foundation types, which were low cap, high cap and high cap with rubber isolation, were established respectively. The working condition of these models included operation base earthquake(OBE) and safety shutdown earthquake(SSE). Both of them were analyzed under three different earthquake waves. The seismic responses of the models, including acceleration, displacement, overturn moment and bottom shearing force, were analyzed and discussed. The isolation efficiency was discussed by comparing the responses of these models. The stresses of piles were also analyzed.From the calculating results, it is found that different foundations result in different earthquake responses. There are little differences in the responses of low cap model and high cap model. But isolated model hugely reduces the responses of upper structure though it increases the displacement. The responses under EI-centro wave are higher than that under Tianjin wave and artificial wave. Conclusions are drawn that high cap with isolation model will effectively reduce the seismic responses of upper structure and the stresses of piles.