近断层强震下高速公路RC连续梁桥的变形性能

Deformation Property of RC Continuous Girder Bridge of Expressway under Near-fault Strong Earthquake

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 explore the seismic deformation properties of bridge structure under strong near-fault earthquake ground motion, a RC continuous girder bridge of expressway close to active fault is introduced for dynamic analysis. Typical near-fault earthquake records in China and the U. S. are selected and artificial seismic waves are constructed as input to establish a refined bridge finite element model. The deformation property of critical· components of the bridge under strong earthquake is studied by nonlinear dynamic time history analysis method, and quantitative assessment is performed. The research result indicates that （1） the earthquake dynamic spectrum characteristics, especially pulse effect of near-fault earthquake, will significantly increase the seismic response of bridge structure; （2） bearing is the weak part of bridge under strong earthquake, and earthquake energy can be dissipated through bearing damage, therefore the risk of pier plastic damage could be reduced effectively, so the plastic deformation ability of bearing could be improved to enhance its energy consumption capability and efficiency.