考虑地震动空间效应的城市高架桥梁地震碰撞响应分析

分析了地震动空间效应对城市高架简支梁桥和多跨连续梁桥地震碰撞响应的影响．拟合了与规范反应谱相一致且考虑空间效应的人工地震波；建立了两种桥型的有限元模型；数值仿真并比较分析了一致激励以及仅考虑行波效应、仅考虑部分相干效应和同时考虑行波效应与部分相干效应的非一致激励等4种激励情况下，两种桥型的非线性地震碰撞响应．结果表明：地震动空间效应对桥梁地震碰撞响应的影响显著，且对连续梁桥的影响更为明显；考虑地震动空间效应会使桥梁的撞击力明显增大，同时考虑行波效应与部分相干效应时增幅最大；随着视波速的提高，地震动空间效应的影响逐渐减弱．因此，在城市高架桥梁地震碰撞响应分析中，必须考虑地震动空间效应的影响.

Seismic Pounding Responses of Urban Elevated Bridges Considering Spatial Variation of Ground Motion

The influence of spatial variation of ground motion on the seismic pounding responses of simply supported girder bridges and multi-span continuous girder bridges in urban viaducts was investigated. The artificial seismic waves considering spatial variation of ground motion were fitted with the prescribed response spectrum in design code. The finite element models of the two types of bridges were built up, and their nonlinear seismic pounding responses were numerically simulated under four cases of excitations including the uniform excitation and the non-uniform excitations considering only the traveling wave effect, only the partial coherence effect, and both of the traveling effect and the partial coherence effect respectively. The results show that the influence of the spatial variation of ground motion on the seismic pounding responses of the bridges is remarkable, and more so on that of the continuous bridges. Considering the spatial variation of ground motion, the impact forces between girders were clearly increased, and its increasing amplitudes were the biggest when the traveling effect and the partial coherence effect were considered simultaneously. The influence of the spatial variation of ground motion was attenuated gradually with the increase of the apparent velocity. Therefore, the influence of the spatial variation of ground motion must be considered in the analysis for the seismic pounding responses of the urban elevated bridges.