地震作用下立式储液罐罐壁“象足”变形仿真分析

Numerical analysis of elephant foot bulging for elevated liquid-storage tank under seismic ground motion

基于ANSYS软件建立了考虑液体晃动和罐底提离立式储液罐有限元模型,分别进行了水平地震和竖向地震作用下罐壁“象足”变形分析。分析表明:立式储液罐罐壁“象足”变形主要是由罐壁纵向压应力超过临界应力而产生的局部屈曲破坏,并非强度破坏。因罐底提离导致的罐底与基础反复撞击加大了作用在罐壁上的应力,使罐壁底部“象足”变形不断发展,最终导致罐壁撕裂。在完全相同地震加速度作用下,水平地震作用比竖向地震作用罐壁更早更容易进入屈曲状态,产生“象足”变形。

The elephant foot bulging deformation of rigid walls of liquid-storage tanks under horizontal and vertical seismic ground motions is analyzed by using the finite element model involving fluid sloshing and tank bottom uplift with ANSYS. The numerical results show that the elephant foot bulging is in fact buckling failure which is caused by the overcritical compressive stress rather than intensity failure. The elephant foot bulging deformation develops with the increasing stress of the rigid wall, which is caused by the uplift of the tank bottom and the impaction between the tank bottom and the foundation. It is also shown that the buckling failure of the rigid wall arises easier from the horizontal seismic ground motion than from the vertical one, therefore the elephant foot bulging deformation is also easier produced.