轻轨高架桥地震响应PGA/PGV分析：Part Ⅰ 近断层效应的影响
Analysis on PGA/PGV specific seismic response of urban light rail transit viaduct： Part Ⅰ Effect of fault rupture

摘要 以城市轻轨钢筋混凝土高架桥为研究对象，分别输入脉冲型、无脉冲型近断层地震和远场地震3种不同类型的地震，建立高烈度区地震作用下的非线性全桥模型，计算了水平及竖向地震作用下桥梁的弹塑性响应，分析了地震峰值加速度与地震峰值速度比值（PGA/PGV）对桥梁地震响应的影响.研究表明，时域分析时，脉冲型近断层地震会造成较大的梁体位移；对于梁体内力，相比其他类型地震，非脉冲地震造成的桥梁惯性力可能较大.频域分析时，相比非脉冲型近断层地震及远场地震，脉冲型近断层地震在较低的频段对桥梁横向响应的影响较大；对于竖向响应，脉冲型近断层地震可以在二阶竖向自振频率影响桥梁地震响应，非脉冲型近断层地震及远场地震在一阶竖向自振频率影响桥梁地震响应.
Abstract：The global nonlinear finite element calculation model of Urban Light Rail Transit Viaduct (ULRTV) in a high seismic region is set up,then the elastic-plastic seismic responses of the bridge subjected to the combined effect of vertical and horizontal earthquakes are calculated under pulse type Near-Fault Ground Motions (NFGMs), non-pulse type NFGMs and Far-Field Ground Motions (FFGMs). And the influence of the Peak Ground Acceleration and Peak Ground Velocity (PGA/PGV) ratio on the seismic response of the bridge is presented. Results demonstrate that the pulse type NFGMs results in the larger lateral displacement at the mod-span of the girder when time-domain analysis.The pulse type NFGMs and the FFGMs maybe bring out the greater internal force compared to the non- pulse type NFGMs. While under frequency-domain analysis, the pulse-type near-fault ground motions greatly impact the seismic lateral seismic response of the bridge in the low frequency band compared to the non-pulse type NFGMs and FFGMs. As for the vertical seismic response of the bridge, pulse type NFGMs influence the response in the second order natural vibration frequency, and the non-pulse type NFGMs and FFGMs influence the response in the first order natural vibration frequency.