大跨度斜拉桥考虑桩土耦合效应下的动力响应分析

利用推导的黏弹性边界的等价形式处理土对结构的影响,分别采用时程分析、虚拟激励法计算结构的响应与内力。通过分析发现,由于苏通桥桩长,考虑土-结构相互作用后,结构整体刚度明显变小,其自振周期变长,结构位移明显比不考虑相互作用时增加。桩-土相互作用的存在使上部结构内力减小;相对于承台固结模型,考虑桩-土-结构相互作用使结构位移增大;与此同时主塔塔底、辅助墩及过渡墩墩底的剪力、弯矩减小,因此桩基础是控制抗震设计最关键的地方之一;鉴于地震波的输入组合对结构响应影响较为明显,在抗震设计时,需多工况输入组合求出地震作用下内力与位移的最大值组合才能保障结构的安全可靠。

DYNAMIC RESPONSE ANALYSIS OF LARGE SPAN CABLE-STAYED BRIDGE BY TAKING ACCOUNT OF PILE-SIUK CIYOKUBG EFFECT

The derived equivalent form of viscoelastic boundary was USED TO treat the effect of soil on the structure;the response and internal force were calculated by structure analysis and the pseudo excitation method. Through the analysis,it was found that the Sutong Bridge is long,after considering soil structure interaction,the stiffness was significantly smaller,its self vibration period is longer,the displacement of structure was obviously increased as compared with the case without taking account of pile-soil increased interaction. Existence of pile-soil interaction could reduce the inner force of the superstructure; with respect to the cap consolidation modelel considering the interaction of pile-soil-structure so that the structure displacement was increased; at the same time the sheah and bending moment of the main tower bottom,Auxiliary Pier and transition pier bottom were reduced,so the pile foundation is one of the most critical parts of the control of seismic design. Because the influence of input combination of seismic wave on the response of structure is more obvious,so for the seismic design of multi condition combination of inputs,the derived maximum combination of internal force and displacement under earthquake can guarantee the safety and reliability of the structure.