基于流固耦合的LNG储罐外罐地震响应分析

Seismic response analysis of LNG storage tank outer tank based on fluid-structure interaction

为研究流固耦合对LNG储罐外罐的地震响应问题,采用振动台试验和数值仿真相结合方法对不同地震波下不同液体高度的LNG储罐进行震动分析。试验结果表明:地震会改变罐体加速度和位移的分布情况,不同地震波和不同液体高度对位移和加速度的放大效应有着不同的影响,在El Centro波、Taft波和SHM2波作用下,流体振荡产生的减震作用和流体压力产生的附加惯性作用能够减小储罐中部的位移,但对加速度有所放大。利用时程分析法对5000m^(3)LNG储罐的位移和环向应力进行地震模拟分析,结果表明:储罐的环向应力呈现出中间大两头小的走势,在罐高的1/4h、1/2h和3/4h上出现极值;位移沿罐高度方向先增加后减少,峰值出现在1/4h、1/3h、1/2h和3/4h处。因此在LNG储罐抗震设计时,应考虑流固耦合效应对结构的影响,在1/4h、1/3h、1/2h和3/4h处的薄弱位置,宜采用增加壁厚、设置阻尼器和钢筋加密等措施增强结构的可靠性和安全性。

The seismic response of fluid-structure interaction to the outer tank of LNG storage tank is studied.The vibration of LNG storage tanks with different liquid heights under different seismic waves is analyzed by shaking table test and numerical simulation.Experimental results show that the earthquake will change the distribution of acceleration and displacement of the tank,and different seismic waves and different liquid heights have different effects on the amplification effect of displacement and acceleration.Under the action of El Centro wave,Taft wave and SHM2 wave,the damping effect caused by fluid oscillation and the additional inertia effect caused by fluid pressure can reduce the displacement in the middle of the tank,but amplify the acceleration.Seismic simulation analysis of displacement and circumferential stress of 5000m^(3)LNG storage tank is carried out by using time-history analysis method.The results show that the circumferential stress of the storage tank presents a trend of large in the middle and small at both ends,and extreme values appear at 1/4,1/2 and 3/4 of the tank height.The displacement first increases and then decreases along the tank height direction,and the peak values appear at 1/4,1/3,1/2 and 3/4 of the tank height.The influence of fluid-solid coupling effect on the structure should be considered in the seismic design of LNG storage tanks.In the weak positions of the tank height of 1/4,1/3,1/2 and 3/4,measures such as increasing wall thickness,setting the damper and reinforcing steel bars should be taken to enhance the reliability and safety of the structure.