行波效应下高墩多塔斜拉桥地震易损性分析
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摘要
为了研究行波效应对大跨高墩多塔斜拉桥抗震性能的影响,以一座超高墩四塔斜拉桥工程实例为分析对象,采用概率性的易损性分析方法,选用OpenSees抗震有限元分析软件,建立全桥非线性动力有限元模型。从PEER数据库中选取80条有代表性的地震波数据,采用位移输入法进行地震波的多点输入以计入行波效应的影响,考虑7种不同剪切波速和一致激励情况,完成全过程非线性分析。结合大桥特点,考虑3种纵向约束体系,选择支座、斜拉索、主梁和桥塔作为易损构件,并通过比较后选取PGD(地震波峰值位移)作为地震动强度指标,建立结构地震概率需求模型,计算和绘制了易损构件的易损性曲线,选择MPGD值(损伤超越概率P_f=50%对应构件的PGD值)作为构件损伤评价指标。结果表明:支座是最易损伤的构件,桥塔相对来说易损性最小;行波效应对支座的抗震有利,对纵向全约束和半约束体系的抗震也有利;随着波速的增加,各构件和体系的抗震水平基本趋于一致激励的结果。
In order to study the influence of traveling wave effect on seismic performance of long-span high-pier multi-tower cable-stayed bridge, a four-tower cable-stayed bridge with ultra high-pier was taken as the analysis object, and the fragility analysis method based on probability was used. The seismic finite element analysis software OpenSees was used to establish the nonlinear dynamic finite element model of whole bridge. A suite of 80 ground motions typically were selected from database PEER, and the displacement input method was used to carry out multi-point excitations to account for the influence of traveling wave effect. Considering seven different shear wave velocities and uniform excitation, the whole process of non-linear analysis was completed. According to the characteristics of bridge, considering three kinds of longitudinal restraint systems of whole bridge, the supports, cables, girders and pylons were selected as vulnerable members, and PGD(peak ground displacement) was selected as the index of earthquake ground motion intensity after comparison. The seismic probabilistic demand model of structures was established, the fragility curves of fragility members were calculated and drawn, and the MPGD(PGD value of component corresponding damage transcendence probability P_f = 50%) was selected as the damage evaluation index of components. The results show that the support is the most vulnerable component, and the tower is relatively minimal in vulnerability. The traveling wave effect is beneficial to the seismic resistance of the support, the longitudinal fully constraint and semi-constraint systems. With the increase of wave speed, the seismic resistance of various components and systems tends to be the result of uniform excitation.
In order to study the influence of traveling wave effect on seismic performance of long-span high-pier multi-tower cable-stayed bridge, a four-tower cable-stayed bridge with ultra high-pier was taken as the analysis object, and the fragility analysis method based on probability was used. The seismic finite element analysis software OpenSees was used to establish the nonlinear dynamic finite element model of whole bridge. A suite of 80 ground motions typically were selected from database PEER, and the displacement input method was used to carry out multi-point excitations to account for the influence of traveling wave effect. Considering seven different shear wave velocities and uniform excitation, the whole process of non-linear analysis was completed. According to the characteristics of bridge, considering three kinds of longitudinal restraint systems of whole bridge, the supports, cables, girders and pylons were selected as vulnerable members, and PGD(peak ground displacement) was selected as the index of earthquake ground motion intensity after comparison. The seismic probabilistic demand model of structures was established, the fragility curves of fragility members were calculated and drawn, and the MPGD(PGD value of component corresponding damage transcendence probability P_f = 50%) was selected as the damage evaluation index of components. The results show that the support is the most vulnerable component, and the tower is relatively minimal in vulnerability. The traveling wave effect is beneficial to the seismic resistance of the support, the longitudinal fully constraint and semi-constraint systems. With the increase of wave speed, the seismic resistance of various components and systems tends to be the result of uniform excitation.
引文
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[10] 李立峰,胡思聪,王连华,等.超高墩多塔混凝土斜拉桥纵向约束体系研究[J].地震工程与工程振动,2015,35(1):85-93. LI Li-feng,HU Si-cong,WANG Lian-hua,et al.Longitudinal Constraint Systems for Super High-pier Multi-span Concrete Cable-stayed Bridges[J].Earthquake Engineering and Engineering Dynamics,2015,35(1):85-93.
[11] 周国良,鲍叶欣,李小军,等.结构动力分析中多点激励问题的研究综述[J].世界地震工程,2009,25(4):25-32. ZHOU Guo-liang,BAO Ye-xin,LI Xiao-jun,et al.Review on Dynamic Analyses of Structures Under Multi-support Excitation[J].World Earthquake Engineering,2009,25(4):25-32.
[12] 张凡,颜晓伟,李帅,等.考虑波速影响的斜拉桥非一致激励地震响应研究[J].建筑科学与工程学报,2016,33(4):60-68. ZHANG Fan,YAN Xiao-wei,LI Shuai,et al.Effects of Wave Velocities on Seismic Response of Cable-stayed Bridge Under Asynchronous Excitation[J].Journal of Architecture and Civil Engineering,2016,33(4):60-68.
[2] ALLAM S M,DATTA T K.Seismic Behaviour of Cable-stayed Bridges Under Multi-component Random Ground Motion[J].Engineering Structures,1999,21(1):62-74.
[3] 方圆,李建中,彭天波,等.行波效应对大跨度多塔斜拉桥地震反应影响[J].振动与冲击,2010,29(10):148-152,235. FANG Yuan,LI Jian-zhong,PENG Tian-bo,et al.Influence of Travelling-wave Effect on Seismic Response of a Long-span Multi-tower Cable Stayed Bridge[J].Journal of Vibration and Shock,2010,29(10):148-152,235.
[4] EN 1998-2:2005,Eurocode 8:Design of Structures for Earthquake Resistance.Part 2:Bridges[S].
[5] JTG/T B02-01—2008,公路桥梁抗震设计细则[S]. JTG/T B02-01—2008,Guidelines for Seismic Design of Highway Bridges[S].
[6] 耿方方,丁幼亮,谢洪恩,等.结构体系对多塔斜拉桥抗震性能的影响分析[J].公路交通科技,2014,31(7):65-71. GENG Fang-fang,DING You-liang,XIE Hong-en,et al.Influences of Structural System on Seismic Performance of Multi-pylon Cable-stayed Bridge[J].Journal of Highway and Transportation Research and Development,2014,31(7):65-71.
[7] ATC-40,Seismic Evaluation and Retrofit of Concrete Buildings[S].
[8] FEMA-273,NEHRP Guidelines for the Seismic Rehabilitation of Buildings[S].
[9] 胡思聪,李立峰,王连华.高墩多塔斜拉桥地震动强度指标选择及易损性评估[J].中国公路学报,2017,30(12):50-59. HU Si-cong,LI Li-feng,WANG Lian-hua.Selection of Optimal Intensity Measures of Ground Motions and Seismic Fragility Assessment for Multi-span Cable-stayed Bridge with Tall Piers[J].China Journal of Highway and Transport,2017,30(12):50-59.
[10] 李立峰,胡思聪,王连华,等.超高墩多塔混凝土斜拉桥纵向约束体系研究[J].地震工程与工程振动,2015,35(1):85-93. LI Li-feng,HU Si-cong,WANG Lian-hua,et al.Longitudinal Constraint Systems for Super High-pier Multi-span Concrete Cable-stayed Bridges[J].Earthquake Engineering and Engineering Dynamics,2015,35(1):85-93.
[11] 周国良,鲍叶欣,李小军,等.结构动力分析中多点激励问题的研究综述[J].世界地震工程,2009,25(4):25-32. ZHOU Guo-liang,BAO Ye-xin,LI Xiao-jun,et al.Review on Dynamic Analyses of Structures Under Multi-support Excitation[J].World Earthquake Engineering,2009,25(4):25-32.
[12] 张凡,颜晓伟,李帅,等.考虑波速影响的斜拉桥非一致激励地震响应研究[J].建筑科学与工程学报,2016,33(4):60-68. ZHANG Fan,YAN Xiao-wei,LI Shuai,et al.Effects of Wave Velocities on Seismic Response of Cable-stayed Bridge Under Asynchronous Excitation[J].Journal of Architecture and Civil Engineering,2016,33(4):60-68.
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