Seismic Response Numerical Simulation Of Large Full Capacity LNG Storage Tanks

Liquefied petroleum gas (LNG) storage tanks suffered significant destruction and losses under the earthquake action. In order to provide the seismic design theory and improve the seismic safety performance of LNG storage tanks, 160,000 m3 full capacity LNG storage tanks is selected,the seismic response analysis of it is carried out by adopting ADINA software. This paper studied the earthquake responses of LNG storage tank considering its self weight, sloshing and earthquake motions. The contents of the dissertation are as follows.Firstly, using ADINA software, a three-dimensional finite element model of LNG tank is established,including inner tanks and outer tanks separate model and inner tanks and outer tanks connective model. The dynamic characteristic parameters of LNG storage tank which is considered liquid-solid coupling effect is analyzed by Lanczos eigenvalue method. The results show that: inner tanks liquid-solid basic vibration frequency is lower, among which cos nθbeam vibration is the leading one; Liquid-sloshing is low-frequency vibration; outer tanks basic vibration frequency is higher, among which cos nθbeam vibration is also the leading one. Considering liquid-solid coupling effect, it has greater influence of outer tanks on inner tanks,and outer tanks increase the inherent vibration period of inner tanks; it has greater influence of inner tanks on outer tanks,and inner tanks reduce the inherent vibration period of outer tanks.Secondly, analyses the seismic response of LNG tank affected by acceleration versus time data of seismic wave. Four sites seismic waves is selected, including one natural wave and one man-made wave in each site seismic waves, the seismic response analysis is carried out by using Newmark-βnumerical integration methods. It is found that: base shear, overturning moment, and sloshing wave height is significantly affected by site, softer site peak value is larger; axial stress is larger at the bottom and top of outer tank wall, while hoop stress is bigger at the top, axial stress is larger at the bottom of inner tank wall, while hoop stress is larger in the upper part,dynamic fluid pressure is relatively large within tank bottom wall. Stress of inner and outer tank is impact on site, the softer site, the peak value is greater. Results suggest that: Choose a favorable site is necessary for seismic design of LNG storage tank.Finally,analyses the seismic response of LNG tank affected by displacement versus time data of seismic wave, One natural seismic waves of the third site is selected. Then compare the results of the two kinds of versus time data of seismic wave. It is found that: the seismic response of LNG tank affected by acceleration versus time data of seismic wave is bigger, and the results close to the calculation results of the standard.