多塔斜拉桥在主震-余震序列波下地震位移研究

Theresidual Displacement Research of Multi-tower Cable-stayed Bridge under Mainshock-aftershock Seismic Sequences

桥梁等结构在遭受地震时,总是会历经前震、主震与余震等一系列地震波动。余震的存在可能会使结构的地震需求超过主震时期,可以说余震对于结构安全有着不可忽略的影响。建立有限元模型,对常规摩擦支座的减隔振体系桥梁结构输入主震-余震序列波,得到墩梁相对位移时程,通过对比分析结构在主震作用下、在余震单独作用下以及在主震-余震序列波作用下支座位移之间的差别,来研究强余震对结构位移峰值以及残余位移的影响。分析研究表明:强余震在很大程度上影响了结构的位移峰值以及残余位移,在抗震设计中余震的作用是不可忽视的,在地震波输入时,应当考虑主震余震序列波。

When subjected to earthquake,bridges will undergo a sequence of ground motions which can be defined as foreshocks,main shocks and aftershocks. The bridge structure already suffered from the main shock and having an initial displacement may be incapable of resisting the excitation of the strong aftershocks,which may further increase the residual displacement and may lead to the occurrence of girder falling which may make the structure collapse or become completely unusable under mainshock-aftershock seismic sequences.Strong aftershocks may thus have the potential to cause extensive structural damage compared to mainshock. So the influence of strong aftershock cannot be ignored. In this paper,a multi-tower cable-stayed bridge is analyzed as an example. The finite element model is established and bearing displacement time history is acquired by inputting mainshock-aftershock seismic sequences on seismic isolation system bridge structure.Then the influence of strong aftershocks on the maximum displacement and residual displacement is studied in this paper by analyzing the difference between displacements of bearings under mainshock,aftershock and mainshock-aftershock seismic sequences. Analysis result indicates that the effect of strong aftershocks which have a significant effect on the maximum displacement and the final residual displacement is of great importance in seismic design,in which mainshock-aftershock seismic sequences should be taken into account.