地基沉降及动水压对储罐屈曲强度的影响

Impacts of foundation settlement and pseudo-dynamic load on buckling strength of storage tanks

大型油罐在地震载荷作用下的罐壁屈曲属于弹塑性变形失稳。为研究地基沉降对非锚固储罐屈曲性能的影响,基于Ramberg-Osgood本构模型,考虑储罐底板、壁板、加强圈、抗风圈、非锚固环墙式地基等实际几何结构因素,采用三维有限元模型(FEM)数值模拟非锚固储罐在谐波沉降下的屈曲行为,研究水平地震力下罐内液体的动水压力、地基谐波沉降的次数及幅值对罐壁屈曲临界压应力的影响特征。结果表明:在谐波沉降及动水压共同影响下,储罐屈曲发生的位置为壁板加强圈之间,罐壁变形呈现非周期性变化。地基谐波沉降、动水压均降低了储罐的屈曲临界压应力,且相同沉降量下,随着谐波次数的增多,储罐抗屈曲的能力越来越弱。

The buckling of tank wall of large-scale oil tank is the elastoplastic instability phenomenon subjected to seismic loading.In order to explore the effect of foundation settlement on the buckling strength of unanchored storage tanks,the buckling behaviors of the tank were analyzed using the finite element computer by means of nonlinear stabilization algorithm.Various items of actual geometrical structure were presented thoroughly in the 3D finite element model(FEM),including concrete ringwall foundation of tank,unanchored bottom with slope,shell tapering from the base to the top,wind girders and supports,top angles,stiffening rings and support plates.Geometric nonlinearity,nonlinear boundary conditions and elastic plastic material of Ramberg-Osgood model were involved simultaneously in simulate course.The impacts of hydrodynamic pressure of liquid in the tank under horizontal seismic forces and the number and amplitude of foundation harmonic settlement on the buckling critical compressive stress were researched.The results show that the tank walls between stiffening rings will are prone to axial buckling by the action of foundation harmonic settlement and hydrodynamic pressure of the liquid,that the deformation of tank shells appears aperiodically,that the foundation harmonic settlement and hydrodynamic pressure of the liquid have a negative influence on tank shell buckling critical load,and that the resistance capacity reduces as the harmonic order number rises under the same settlement.