The Effect Analysis Of Near-fault Long Period Ground Motions And Pile-soil Contact Effect On LNG Storage Tanks

Liquefied natural gas(LNG) as a kind of green fuel has become the country’s first choice for energy. It must have a high security assurance in the process of storage and transportation due to its inflammable and explosive nature. In the past, seismic research of storage tanks mostly concentrated on short period ground motion and rigid foundation, so, the near- fault long period ground motion and pile-soil contact effect were deeply analyzed in this paper, the analysis process mainly includes the following aspects:1. The research situation of near-fault ground motion and pile-soil contact effect were summarized, the current research situation of structure seismic isolation under near- fault ground motion was discussed in details.2. The finite element analysis software ADIN A was used to build 160 thousand m3 LNG storage tanks with and without pile-soil models. In which, the Beam and Spring element were used to simulate the pile foundation and soil respectively. The CFD calculation method was adopted and displacement ground motion was inputed. In which, it was inputed in the bottom of storage tanks with rigid foundation and the bottom of pile foundation in the storage tanks with pile-soil.3. With and without pile-soil storage tanks were analyzed, long and short period ground motion were inputed respectively, the conclusion was drawn by comparing the seismic response: the 160 thousand m3 LNG storage tank had long period nature, the sloshing wave height of it was very remarkable under near-fault ground motion. The long period ground motion had a large velocity pulse at the same time, the stock solution will have a strong impact on the inner tank wall and larger effective stress will be produced.4. The seismic bedrock motion was inputed in the 3D integral model of pile-soil-storage tank to analyze pile-soil contact effect, results showed that, the bedrock wave propagated up along the pile-soil and it acted in the upper structure. The acceleration and displacement of pile top was increased compared with pile bottom, the seismic response of pile-soil storage tank was increased remarkable compared to that of without pile-soil storage tank.5. One way and three direction ground motion with the same acceleration peak value were inputed in the LNG storage tank. Compared with the seismic response, the results showed that: the seismic response calculated by the one-way horizontal seismic excitation was smaller than that calculated by the three-dimensional seismic motion. In order to better simulate the effect of the actual ground motion on the storage tank. It is suggested that the6. influence of multi dimension ground motion should be considered in design and construction of storage tanks.7. The rubber cushion seismic isolation and non-seismic isolation storage tanks with and without pile-soil finite element models were built, and the seismic control effect was analyzed. In which, the seismic isolation period of the seismic isolation device was 2s, the viscous damping ratio was 0.1. Results showed that after the seismic isolation measures were taken, all kinds of the seismic response of storage tanks decreased except sloshing wave height. But the control effect of near- fault long period ground motion was not as good as short period.In this paper, the conclusion is drawn from above, reasonable suggestion for the design and construction of LNG storage tanks is put forward.