基于场地-结构整体模型的桩基斜拉桥地震反应分析方法

seismic analysis method for cable-stayed bridges with pile foundation based on site-structure integrated model

摘要:

从我国普遍采用的大跨度桩基桥梁出发，应用无限元—有限元土体边界、桩土面—面接触算法和显式求解技术，提出了场地—结构整体模型的地震反应分析方法。以一座主跨为202.5m+300m的独塔斜拉桥为工程实例，构建了河谷场地—桥梁整体有限元动力模型，研究了二维河谷场地对该斜拉桥纵向地震反应的影响，同时分析了基础附近扰动场地震动的特点。结果表明场地中不同河岸高度和二维土层分布会对主塔处地震动的短周期分量产生一定影响，对结构短周期振型产生的地震力有较大影响；扰动场的地震动接近基础振动频率的分量得到了加强，和自由场的地震动有显著区别，而长周期的分量变化较小。

Abstract:

A seismic analysis method for cable-stayed bridges with pile foundation based on site-structure integrated model have been developed, incorporating the technique of finite element-infinite element boundary, surface to surface contact algorithm and time-domain explicit analysis. For a 202.5m+300m single tower cable-stayed bridge with group pile foundations, the longitudinal seismic response is analyzed based on the integrated model, focused on the effect of valley site and the characteristics of the ground motion under soil-structure interaction. The results indicate that the shape of the valley and the two-dimensional soil layer will affect short period components of the ground motion, and affect the seismic response of the structure accordingly. For the ground motion, the soil-structure interaction strengthens the components with period close to vibration period of the pile foundation, while has little effect on the components of larger period.