近断层地震动对大型LNG储罐作用效应分析

Analysis of the effect of near-fault ground motion on large LNG storage tank

近断层地震动对长周期结构威胁很大,而大型LNG储罐属于安全等级要求极高的液固耦合长周期结构,为研究各类近断层地震动对LNG储罐的作用效应,采用数值仿真方法计算了16×104m 3LNG储罐在不同种类近断层地震动激励下的地震响应,通过对比单向、双向和三向地震动作用下LNG储罐地震响应的差异,验证了对LNG储罐进行三向地震作用研究的必要性。此外,重点研究了在具有向前方向性效应、滑冲效应与无脉冲地震动作用下LNG储罐地震响应的特点。结果表明:含有较大速度脉冲和大位移的地震动会激发储液的剧烈晃动,进而对罐壁顶部产生巨大的冲击,导致罐壁顶部出现应力突变和位移超限,最终引起储罐的菱形屈曲或顶部附属结构物的破坏。

Near-fault ground motions have threaten long-period structures greatly,while large LNG tanks are liquid-solid coupled long-period structures with high safety requirements.In order to study the effect of near-fault ground motions on LNG tanks,the seismic responses of LNG storage tanks under near-fault ground motions were studied by numerical simulation method.The differences of seismic response of LNG storage tank under unidirectional,bidirectional and tri-directional seismic action were compared,and the necessity of research on tri-directional seismic action of LNG storage tank was verified.In addition,the seismic responses of LNG storage tanks under forward directivity and fling-step ground motions were compared with those non-pulse ground motions.The results show that the ground motion with large velocity pulse and large displacement will stimulate the violent sloshing of the LNG,which will have a huge impact on the top of the tank wall,resulting in stress mutation and displacement exceeding the limit at the top of the tank wall,and eventually lead to the diamond buckling of the tank or the destruction of the top appendages.