地震动空间相干效应对大跨度斜拉桥随机地震反应的影响

Influence of spatial coherence of seismic motions on stochastic seismic response of long-span cable-stayed bridges

随着斜拉桥跨度的增大,地震动空间效应对结构地震反应的影响成为新的研究课题。基于随机振动理论,以苏通长江公路大桥为背景,分析地震动空间相干效应对大跨度斜拉桥地震响应的影响规律。研究表明:考虑地震动相干效应后,结构的内力和位移响应明显增大,且相干效应对主梁和索塔内力与位移的影响程度及规律也不尽相同,须区别对待分析。由此得出结论,对大跨度斜拉桥进行随机地震响应分析时,必须考虑地震动的空间相干效应。

With the growth of the main span about the cable-stayed bridges,the effect of spatial coherence of earthquake motions on the spatial structures is a new research topic.Based on stochastic vibration theory and combined with Sutong Yangtze River Highway Bridge,the stochastic seismic response of a super-long-span cable-stayed bridge under the seismic motion with considering the spatial coherency effect is developed.The obtained results indicate that the internal force and displacement are influenced obviously by the partial coherence effect than uniform excitation.For different responses of internal force and displacement of the girder and the tower,the impact and the rules are different for the seismic motion with considering the spatial coherence effect.Therefore,in view of different cases,the analyses have different results.As a result,the partial coherence effect of the seismic motion must be considered in the stochastic seismic response analysis of the long-span cable-stayed bridges.