考虑冲刷影响的川藏线连续梁桥横向地震易损性分析  

Lateral Seismic Fragility Analyses of the Continuous Beam Bridge on the Sichuan⁃Tibet Route Considering Scour Effect

作　　者：何海峰 魏凯 何成 HE Haifeng;WEI Kai;HE Cheng(Department of Bridge Engineering,Southwest Jiaotong University,Chengdu 610031,China;Sichuan Wenchuan Maerkang Highway Limited Liability Company,Chengdu 610041,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]四川汶马高速公路有限责任公司,四川成都610041

出　　处：《防灾减灾工程学报》2021年第3期441-447,共7页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(51708455)资助。

摘　　要：冲刷将减小土体对桥梁基础的横向支撑作用,削弱桥梁结构刚度,进而影响桥梁结构的动力学特性和抗震性能,因此有必要研究冲刷对桥梁结构抗震性能的影响。以川藏线常见的三跨连续梁桥为工程背景,利用有限元软件SAP2000建立桥梁结构有限元模型,利用m法考虑桩土相互作用,讨论了冲刷深度变化对桥梁结构动力学特性的影响。选取曲率延性作为桥墩和桩基的损伤指标,考虑材料和几何非线性,通过增量动力分析方法得到不同横向地震动强度下桥墩和桩基的峰值曲率,建立了不同冲刷深度下桥墩、桩基在轻微损伤、中等损伤、严重损伤以及完全破坏状态下的地震易损性曲线。研究结果表明:冲刷深度增加将增大桥梁结构自振周期;桥墩在各损伤状态下的损伤概率随冲刷深度的增大而不断减小;冲刷深度较小时,桩基的损伤概率随冲刷深度增加而增大,但当冲刷深度超过某一值时,桩基的损伤概率反而有所减小。The scour effect will weaken the lateral support of the bridge foundation,which reduces the structural stiffness,and thus it will affect the dynamic characteristics and seismic performance of the bridge structure. Therefore,it is necessary to study the seismic performance of the bridge considering scour effect. A three-span continuous beam bridge on the Sichuan-Tibet route was used as an example,and the finite element model of the bridge was established by SAP2000. The m method was used to simulate the pile-soil interaction. The influence of scouring depths on the dynamic characteristics of the bridge structure was discussed. The curvature ductility was selected as the damage index of the pier and pile foundation. The incremental dynamic analyses were used to obtain the peak curvature of the pier and pile foundation under different lateral ground motion intensities considering the material and geometric nonlinearity. The seismic fragility curves of the pier and pile foundation under the slight damage,medium damage,severe damage,and complete damage state were established under different scouring depths,respectively. The results show that the scouring effect will increase the natural vibration period of the bridge structure;the seismic damage probability of the pier reduces with the increase of scouring depths;when the scouring depth is small,the seismic damage probability of the pile foundation increases with the increase of scouring depths. When the scouring depth exceeds a certain value,the seismic damage probability of the pile foundation may reduce.

关 键 词：冲刷 动力学特性 地震易损性曲线 桥墩 桩基 

分 类 号：TU435[建筑科学—岩土工程]