行波效应下劲性骨架混凝土拱桥地震响应规律分析

采用SAP2000建立了基于大质量法的动力分析模型,选取了4条NGA-West2数据库中与实际工程场地条件类似的地震波通过调幅后作为输入地震动,研究了行波效应对大跨度铁路劲性骨架混凝土拱桥地震响应的影响规律。研究结果表明:大跨度铁路劲性骨架混凝土拱桥在非一致激励下交界墩伸缩缝位移和主拱拱脚及主拱L/4处弯矩随相位差的变化具有周期性,且变化周期与结构1阶纵向自振周期基本一致,在相位差为结构1阶纵向自振周期的2n倍(n为整数)时结构响应处于峰值,在(2n+1)/2时结构响应处于谷值;跨中伸缩缝位移、拱顶轴力在非一致激励下分别为一致激励下的50~150倍,100~300倍;由于行波效应加剧了结构地震响应,在进行大跨度劲性骨架混凝土拱桥抗震设计时应考虑行波效应对结构关键部位的影响。

Analysis of Seismic Response Regularity of Stiff Skeleton Concrete Arch Bridge Under Traveling Wave Effect

A dynamic model of concrete arch bridge was established with software SAP2000 based on large mass method.Four earthquake waves in NGA-West2 database,which are similar to the actual engineering site conditions,were selected as the input ground motion after amplitude modulation.The influence of traveling wave effect on the seismic response of long span railway stiff skeleton concrete arch bridge was studied.The analysis results indicated that for long span railway stiff skeleton concrete arch bridge,expansion joint displacement at juncture pier,bending moment at arch foot and L/4 arch under non-uniform excitation varies in period along with phase difference and the variation period is generally the same as structure first order longitudinal natural vibration period.When the phase difference is 2n times(n is an integer)of the first order longitudinal natural vibration period of the structure,the structural response is at the peak value,and at(2n+1)/2,the structural response is at the valley value.The displacement of the expansion joint in the middle span and the axial force of the vault under the non-uniform excitation are 50~150 times and 100~300 times of that under the uniform excitation respectively.Because the traveling wave effect intensifies the seismic response of the structure,the influence of the traveling wave effect on the key parts of the structure should be considered in the seismic design of the long span rigid skeleton concrete arch bridge.