行波效应对南昌朝阳大桥的地震响应影响分析

Research on Seismic Response of Cable-stayed Bridge with Multi-support Excitation

以某大跨度塔梁固结体系斜拉桥为实例,运用Opensees软件建立动力有限元模型,采用位移输入法,研究行波效应对大跨径斜拉桥地震响应的影响,对比了隔震与未隔震斜拉桥在行波效应下各关键截面的内力及位移.结果表明,与一致激励下斜拉桥地震响应相比,考虑行波效应时,桥面纵向加速度和主梁纵向位移会减小;支座的变形、内力及耗能负担会增大;主梁和桥塔的内力在某个视波速情况下会大于一致激励下的地震响应.与考虑低视波速情况下主梁和桥塔的抗震设计相比,一致激励下的抗震设计偏保守.在中视波速地震荷载作用下,隔震斜拉桥主梁和桥塔截面内力响应比未隔震斜拉桥更加有利.

In order to provide a reference for seismic design of long-span cable-stayed bridge,the model of the bridge is founded on the basis of Nanchang Chaoyang Bridge.Dynamic finite element model is established by using Opensees and the dynamic characteristics are analyzed.The study investigates seismic responses of long-span cable-stayed bridge under the traveling wave effect based on the displacement input method.The results indicate that considering traveling wave effect can effectively reduce the longitudinal acceleration of the bridge deck and longitudinal displacement of the bridge girder.Besides,traveling wave effect will increase the burden of energy consumption,deformation and internal forces of the bearing.The impact of traveling wave effect to the seismic response of the bridge structure has the characteristic of shock.Thus,it still needs to judge whether the seismic-isolated cable-stayed bridge is advantageous according to the actual seismic wave velocity.