摘要
Past earthquakes have revealed that topographic features have significant impacts on the characteristics of ground motions,which may cause the amplification and de-amplification of input seismic waves.The topographic effect with the assumption of plane seismic waves on the seismic responses of bridges has been investigated in the existing literature;however,the influence of near-source topographic effects has not been thoroughly understood.The objective of this study is to numerically explore the near-source topographic effects on the seismic behaviors of an existing railway bridge crossing a symmetrical V-shaped canyon.The influence of the source of incident waves is estimated.Numerical results demonstrate that the topographic effects can noticeably amplify the seismic responses of the bridge.Compared to the bridge without crossing a canyon,the peak displacements of the girder,pier,and bearing in the case of the canyon crossing bridge increase by 15.2%,2.9%−14.5%,and 24.2%−229.6%,respectively.The piers at the illuminated side of the canyon experience larger seismic responses compared to the piers at the shaded side of the canyon due to the unequal motion amplitudes at each support.As the source-to-canyon distance increases,the seismic responses of the piers show an increasing trend.
地震记录表明地形局部不规则对地震动特征具有显著影响,会造成地震动出现放大或衰减现象。关于地形效应对桥梁地震响应影响方面的研究,多基于平面地震动输入的假设,针对近源地形效应方面的研究尚未深入开展。本文采用数值分析方法研究了近源地形效应对跨V形河谷铁路桥地震响应的影响规律,进而评估了震源位置对该桥地震响应的影响。分析结果表明:地形效应可显著放大桥梁的地震响应;相较于非跨河谷桥梁,跨河谷桥梁主梁、桥墩及支座的峰值位移分别增加15.2%、2.9%~14.5%和24.2%~229.6%;波场幅值在迎波侧和背波侧具有明显差异,位于迎波侧桥墩的地震响应显著高于背波侧桥墩;随着震源距的增加,桥墩的地震响应呈增大趋势。
基金
Projects(51908123,51678140,U1934205)supported by the National Natural Science Foundation of China
Projects(BK20190370,BK20180383) supported by the Natural Science Foundation of Jiangsu Province,China
Project(18KJA580005) supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of China
Project(KYY2019096(19-21)) supported by the Science and Technology Research Plan of China Railway Eryuan Engineering Group Corporation。
作者简介
Corresponding author:王景全,PhD,Professor,E-mail:wangjingquan@seu.edu.cn,Tel:+86-13912982818,ORCID:https://orcid.org/0000-0001-6379-5363;Corresponding author:张宁,PhD,Professor,E-mail:ningzhanghhu@163.com,Tel:+86-13776412650,ORCID:https://orcid.org/0000-0002-0639-3920。
