Studies On Seismic Performance Of LNG Storage Tank

· As one of the most efficient and clean energies,the nature gas has drew a lot of concentrations in recent years. With the blooming of populations and the economy, the demands of new kind energy increased staggeringly. LNG (Liquefied Natural Gas), which is need to be liquefied under -162 degree centigrade, in order to be delivered more easily and be stored more conveniently. Large-scale LNG storage tank, as an installation at the receivers, plays a significant role in transporting. The tanks’ safely and efficiently of working is quite vital in the whole process. However, the cost of building a tank is much too high that make it an obstacle in domestic LNG development. The reason is that we are lack of techniques to design and construct the tank on our own. Besides, as an ultra-low temperature, flammable and explosive gas, in the events of leakage,LNG will cause serious secondary disasters. As a result, the study of seismic behavior of LNG storage tank seems to be quite important.· This paper will focus on the inner tank of a 160000 cubic meters LNG tank,study its seismic response and calculate the relative values, such as dynamic liquid pressure, bottom shear and overturning moment. And comparison with the results of finite element software Abaqus will be made to evaluate the seismic behavior of LNG storage tanks.· Firstly, the <Eurocode 8: Design of structures for earthquake resistance —Part 4: Silos,tanks and pipelines>,( BS EN 1998-4: 2006) was used for working out the closed form solutions for cylindrical tanks on a rigid tank and a flexible one subjected to a lateral excitations respectively. Meanwhile, the impulsive and convective fluid pressure distributions, and the results about the effect of the inertia of the walls and height of the convective wave are represented.· Secondly, a simplified inner tank of a real engineering one was used to calculate the details which are needed for analyzing its seismic responses.·At last, the seismic time-historical analysis of LNG storage tank was obtained with the finite element software Abaqus. Considering the inefficiency in the traditional numerical simulation of fluid-solid coupling calculation, the method used for analyzing is to regard the liquid as mass points which are lined in the middle of the tank, and linked to the wall with springs. The response spectrum of the LNG storage tank under the frequently-occurred earthquake is obtained. And the numerical results were compared with theoretical one.