考虑地震波斜入射下河谷地形的大跨桥梁动力反应研究

Seismic response analysis of long-span bridges subjected to spatially non-uniform seismic ground motions

大跨度桥梁的地震动空间变化的非一致影响不可忽略,斜入射是引起这种空间变化的主要因素.研究了斜入射条件下自由场数值模拟方法,建立了考虑地震动空间非一致性的大跨度桥梁三维有限元分析模型,以某跨海连续刚构桥为背景,研究了考虑非一致地震动空间的大跨桥梁地震动力反应,分析桥梁的内力幅值和分布规律.研究了地震波输入、斜入射角、地基土剪切波速以及河谷地形等影响因素的变化对P波及SV波作用下连续刚构桥结构动力反应的影响规律.结果表明,河谷地形条件下,墩底内力的变形规律和平坦地形相比有一些差异.斜入射时河谷地形的剪力和轴力的非一致影响系数与平坦地形相差比较大,P波作用下,墩底剪力和纵桥向弯矩随着入射角的增大而增大,墩底轴力随着入射角的增大而减小,SV波入射时,河谷地形条件下的墩底剪力和纵桥向弯矩随着入射角的增大而减小,墩底轴力随着入射角的增大而增大.

The non-uniform effects of long-span bridges under spatial variation of ground motions can not be neglected.Oblique incidence plays a vital role in triggering such spatial variation.The numerical simulation method of free field under oblique incidence is studied.A three-dimensional FEA model considering the spatially non-uniform ground motion is built to analyze the seismic responses of a certain continuous rigid-frame bridge with large span.On the background of a crossing sea continuous rigid frame bridge,the seismic analysis of long-span bridge is presented and the amplitude and distribution of internal forces are studied.When influencing factors like seismic wave input,oblique incident angle and shear wave velocity of the soil are changing,the dynamic response influencing laws of continuous rigid frame bridges under P-wave and SV-wave are summarized.