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为探讨近断层强震下桥梁结构的大震变形性能,以某靠近活动断层的高速公路RC连续梁桥为对象进行了动力分析。挑选中、美两国典型近断层地震动记录,并构造人工地震波作为输入,建立了桥梁精细化有限元模型。采用非线性动力时程分析方法研究了强震水平下桥梁关键部位的变形性能,并进行了定量评估。研究表明:地震动频谱特性,尤其是近断层地震动的脉冲效应,会显著增大桥梁结构的地震响应;强震下,支座是桥梁结构的薄弱环节,但通过支座破坏可耗散一定的地震动能量,从而有效降低桥墩塑性破坏的风险,因而可通过提高支座的塑性变形能力,增强其分担地震动总耗能的能力和效率。
In order to investigate the deformability of large-scale earthquake under near-fault strong earthquakes, a dynamic analysis is conducted on a RC continuous beam bridge near a moving fault. The typical near-fault ground motion records of China and the United States are selected, and artificial seismic waves are constructed as input. The finite element model of the bridge is established. The nonlinear dynamic time-history method was used to study the deformation performance of key parts of bridges under strong earthquake and the quantitative assessment was carried out. The results show that the spectral characteristics of ground motion, especially the pulse effect of near-fault ground motions, will significantly increase the seismic response of the bridge structure. Under strong earthquake, the bearing is the weak link of bridge structure, Thus, the risk of plastic failure of the pier can be effectively reduced. Therefore, the plastic deformation capacity of the bearing can be increased and its ability and efficiency of sharing the total energy consumption of ground motion can be enhanced.