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基于非平稳随机地震动场理论,研究地震动空间变化对单索面固结体系斜拉桥地震响应特征的影响。建立非一致激励功率谱模型,根据大桥地质勘查资料和区域地震标准分别合成主塔、桥墩桩基基底的非一致地震波。运用在基底处增加大质量质块的方法,将地震加速度转化为地震力,实现对单索面固结体系斜拉桥的多点激励。分析结果表明,与一致地震激励相比,非一致激励下的桥梁位移与内力均可有数量级的增大,并且不会出现塔顶相对水平位移和塔根截面弯矩减小的现象。因此,对于单索面固结体系斜拉桥,不考虑非一致激励的抗震分析是偏不安全的,地震动空间变化造成的影响必须予以足够的重视。
Based on the non-stationary stochastic seismic field theory, the influence of the spatial variation of ground motion on the seismic response characteristics of cable-stayed bridge with single cable plane consolidation system is studied. The non-uniform excitation power spectrum model is established. According to the bridge geological survey data and regional seismic standards, the non-uniform seismic waves of the foundation of the pylons and bridge piers are synthesized respectively. Using the method of adding large mass blocks at the base, the seismic acceleration is transformed into the seismic force to realize the multi-point excitation of cable-stayed bridge with single cable plane consolidation system. The analysis results show that the displacement and the internal force of the bridge under non-uniform excitation can all increase by an order of magnitude compared with the consistent earthquake excitation, and the relative horizontal displacement of the tower and the decrease of the bending moment of the tower root section will not occur. Therefore, for cable-stayed bridges with single cable plane consolidation system, it is insecure to consider the seismic analysis of non-uniform excitation. The influence caused by the space change of the earthquake must be paid enough attention.