高墩大跨曲线连续刚构桥地震响应研究

Seismic Response Study of High Pier and Long-span Curved Continuous Rigid Frame Bridge

目的研究桩土相互作用和行波效应对高墩大跨曲线连续刚构桥地震响应的影响.方法采用有限元程序,建立跨度为(70+3×127+70) m的曲线刚构桥有限元模型,采用动态时程分析方法,分析了桩土相互作用和行波效应在不同参数取值下的桥梁结构地震响应.结果纵桥向激励下,考虑桩土相互作用比不考虑桩土相互作用桥梁各桥墩控制截面内力增大30%～40%;横桥向激励下,考虑桩土相互作用比不考虑桩土相互作用桥梁各桥墩控制截面内力减小17%～25%.考虑桩土相互作用,将显著增大墩顶和墩底截面纵桥向内力,减小横桥向墩顶和墩底内力;考虑地震波传播速度引起的行波效应,使得桥墩内力在不同桥墩之间呈现更加不均匀分布状态,增大部分桥墩破坏的危险;由于地震波入射角度不同而引起的行波效应时,入射角度为0°时各个桥墩内力和位移响应略大于10°和-10°两个入射角度的激励结果.结论地震波入射角度引起的行波效应时对该类桥型地震响应影响较小.桩土相互作用对该类桥型的动力特性有一定的影响.随着桩土弹性连接土介质参数的增大,结构体系的自振频率也随之增大,但结构的低阶振型基本未变.

This paper aims at the seismic response of high pier and long-span curved continuous rigid frame bridge influenced by the pile-soil interaction and traveling wave effect. A curved rigid frame bridge with a span of( 70 + 3 × 127 + 70) m was simulated by a finite element program,and the bridge seismic response under different parameters of pile-soil interaction and traveling wavewere analyzed by using dynamic time history analysis method. Under longitudinal bridge excitation,the internal force of the control section of each bridge pier with considering the interaction between pile and soil is 30% ~ 40% higher than that of no-considering interaction between pile and soil;Under the cross-bridge excitation,the internal force of the bridge cross section of the bridge with considering the interaction between pile and soil is 17% ~ 25% less than that of no-considering interaction between pile and soil. The pile-soil interaction can enlarge the internal force of top and bottom of the pier along the direction of the bridge and decrease the internal force along the transverse direction of the bridge. The traveling wave effect with considering the seismic wave propagation velocity can make the internal force of the bridge pier more uneven distribution in different piers,and increases the risk of damage to part of the pier;considering the traveling wave effect caused by seismic wave incident angle,the internal force and displacement of the bridge pier with incident angle 0 degree are slightly larger than that of the two other incident angle 10 degree and-10 degree. The traveling wave effect caused by the incident angle of seismic waves has little effect on the seismic response of this type of bridge. Pile-soil interaction has a certain influence on the dynamic characteristics of this type of bridge. With the increase of the media parameters of the elastic soil of the pile-soil,the natural vibration frequency of the structural system also increases,but the low-order vibration mode of the structure remains basically unchanged.