冲刷环境下跨海桥梁海陆地震动作用易损性对比研究  

Seismic Fragility Comparative Research of Sea-crossing Bridges with Scour Conditions Under Onshore and Offshore Ground Motions

作　　者：王德斌 夏青 孙治国 王东升 刘朵 WANG Debin;XIA Qing;SUN Zhiguo;WANG Dongsheng;LIU Duo(School of Civil Eng.,Dalian Jiaotong Univ.,Dalian 116028,China;School of Civil Eng.,Inst.of Disaster Prevention,Beijing 101601,China;School of Civil and Transporting Eng.,Hebei Univ.of Technol.,Tianjin 300401,China;JSTI Group,Nanjing 210017,China)

机构地区：[1]大连交通大学土木工程学院,辽宁大连116028 [2]防灾科技学院土木工程学院,北京101601 [3]河北工业大学土木与交通学院,天津300401 [4]苏交科集团股份有限公司,江苏南京210017

出　　处：《工程科学与技术》2021年第5期127-137,共11页Advanced Engineering Sciences

基　　金：国家自然科学基金项目(51678150);辽宁省自然科学基金项目(20170540134);大连市青年科技之星项目(2018RQ72)。

摘　　要：现有跨海桥梁抗震分析研究仍选用陆地地震动而忽略了海底与陆地地震动间的差异,且处于海洋环境中的桥梁下部结构在长时间流水冲刷下,桩周土体流失进而导致结构稳定性降低。本文以某跨海大桥引桥段为例,利用ABAQUS建立有限元计算模型,考虑桩土作用和动水压力等因素影响,采用概率地震需求分析方法对不同冲刷环境下陆地和海底地震动作用下的桥墩、支座进行易损性分析。通过绘制桥墩、支座超越概率易损性曲线和超越概率增幅柱状图研究桥梁关键构件在海陆地震动和不同冲刷深度下的损伤发展规律。结果表明:对比陆地地震动作用,海底地震动作用下的桥墩更易损坏,且随着土体局部冲刷深度增加,桥墩破坏概率持续提高;冲刷深度对桥墩纵桥向破坏超越概率影响更为明显,同等强度地震动激励下,桥墩纵桥向破坏超越概率高于横桥向。支座较桥墩在相同工况作用下更易发生破坏,海底地震动作用下其破坏超越概率增幅普遍高于陆地地震动作用下;随着冲刷深度增加,支座破坏超越概率逐渐提高,且随着地震动强度的增加,相较于陆地地震动,海底地震动作用下支座破坏超越概率受冲刷深度的影响更加明显。Onshore ground motions were widely used for seismic analysis of sea-crossing bridges,and the difference between the onshore and offshore ground motions were ignored.Due to soil loss around piles scoured by water for a long time,the stability of substructure of bridge in marine environment was reduced.Taking an approach part of a sea-crossing bridge as an example,a finite element model for this approach part was built by using the ABAQUS software.The pile-soil effect and hydro dynamic force were considered in the model.The probabilistic seismic demand analysis method was used with the fragility analysis of bridge piers under onshore and offshore ground motions with different scour conditions.By drawing the transcendence probability vulnerability curves and the transcendence probability increase diagrams of piers and bearings,the damage regularities of bridges under the onshore and offshore ground motions and different scour depths of bridges key components were studied.The results showed that the bridge piers were more vulnerable under offshore motions than that under onshore motions.With the increase of the local soil scour depth,the failure probability of the bridge piers and bearings increased.The effect of scour depth had a more obvious effect on the failure exceeding probability of the piers.The failure exceeding probability of the piers in bridge longitudinal direction was higher than that in bridge transverse direction under the same intensity of ground motion.The bearings were more vulnerable than bridge piers under the same working conditions.The increase of failure exceeding probability of the bearings under the offshore motions was also generally higher than that under the onshore.As the scour depth increased,the failure exceeding probability of the bearing gradually increased.Comparing with the onshore motions,the scour depth had a more obvious influence on the failure exceeding probability of bridge piers under the offshore motions with the in-crease of the ground motion intensity.

关 键 词：桥梁抗震 海陆地震动 局部冲刷深度 桩土作用 易损性分析 

分 类 号：U442.55[建筑科学—桥梁与隧道工程]