考虑地形影响和多点激励的大跨高墩桥地震响应分析

提出一种综合考虑行波和地形影响的大跨结构在多点输入下的地震响应分析方法。首先计算P波在多种角度入射下两座山峰以及其间自由场地的时程响应,并以此作为两座山峰之间大跨桥梁的桥台及桥墩基础多支承点处的地震输入,这种地震输入综合了行波和地形的影响。然后基于多点激励下地震响应分析方法,编制有限元分析程序,在此基础上分析了考虑行波和地形综合影响下一座360m4跨高墩连续刚构桥的多点激励地震响应。从分析结果看,考虑地形效应和不考虑地形效应的差别较大,不考虑地形效应可能会较小的估计结构的内力响应。因此,大跨度结构地震响应分析应考虑地形的影响。本文分析结果可供抗震设计参考。

Seismic responses analysis of continuous rigid-framed bridge with hige piers considering topographic effects and multi-support excitations

A method of seismic response analysis for long-span bridges considering the synthetic effects of wave-traveling,topography and multi-support excitations is established.The responses along the surfaces of two mountains are calculated and they were caused by P-waves with four incidence degrees.The results so obtained are to be used as the input data for the vibration analysis of a long-span bridge seating on multi-supports.Based on the proposed analysis method,a finite element program was prepared for the seismic analysis of a long-span continuous bridge of 360m with four high piers.It was found that the results by considering the topographic effects are very much different from those without such effects.Therefore,merely considering wave-traveling effects may lead to non-conservative results.If a more accurate prediction is desired,the topographic effects must be considered.The results and conclusions in the paper can serve as a seismic design reference for earthquake engineering practice.