地震差动下边界-地基-斜拉桥体系破坏特征

Elasto-plasticity Analysis and Failure Characteristics of Long-span Cable-stayed Bridge Considering Boundary-foundation Interaction Under Multiple-support Seismic Excitations

同时考虑边界条件和地基–结构相互作用对大跨桥梁结构地震响应的影响是个复杂问题。本文以一大跨斜拉桥为例,通过开发的系列程序建立了边界–地基–桩–斜拉桥结构的ABAQUS模型,生成了目标场地多点地震动,对比了不同地基边界条件对大跨斜拉桥结构自振特性的影响,探讨了地表/地下多点地震动作用下、不同地基边界条件对大跨斜拉桥体系弹塑性发展过程及倒塌模式的影响规律。结果表明:(1)进行大跨斜拉桥结构的抗震分析时,有必要考虑地基边界条件的影响;(2)地表多点地震动输入下,考虑地基–结构相互作用时,大跨斜拉桥结构的弹塑性发展过程和倒塌模式与单独斜拉桥不同;(3)粘弹性人工边界条件考虑了周围土体对地基的作用,地基相对变形较小,对上部斜拉桥结构起到了一定的保护作用。

Seismic response effect of the long-span bridge structure considering both boundary condition and soil-structure interaction simultaneously is a complex problem. Taking a long-span cable-stayed bridge as an example, the boundary-foundation-pile-cable-stayed bridge model was established by a series of developed programs. The target site multi-support ground motions were also generated. The different boundary conditions on the vibration characteristics effect of the long-span cable-stayed bridge were compared. The effect of different boundary conditions on the elasto-plasticity development process and collapse mode of the long-span cable-stayed bridge was also discussed under surface/ underground multi-support ground motions. The results indicate that： （1） It is necessary to consider the effect on the boundary conditions of the foundationin the seismic analysis of large-span cable-stayed structure; （2） When considering foundation-structure interaction, the elasto-plastic development process and collapse mode of the large-span cable-stayed bridgeare different with the single cable-stayed bridge under the surface muhi-supportground motion; （3）Accounting forthe effect of soil surroundedby the foundationin the viscous-spring artificial boundary condition, the foundation deformation is relatively smallerand this plays a protective role in the upper cahle-stayedstructure.