地震研究

跨走滑断层多跨简支梁桥地震反应特征与参数分析

(兰州理工大学土木工程学院,甘肃兰州 730050)

Seismic Response Characteristics and Parameter Analysis of the Multi-span Simply Supported Girder Bridge across Strike-slip Faults

SHI Yan,WANG Wenxian,ZHAO Haomiao,YANG Xiong,CHAI Wenyang

(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,Gansu,China)

Keywords：across-fault ground motions; multi-span simply supported girder bridge; seismic response; seismic damage; parameter analysis

DOI: 10.20015/j.cnki.ISSN1000-0666.2024.0048

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为揭示跨走滑断层多跨简支梁桥的地震响应规律,以1座4跨简支梁桥为研究对象,基于OpenSees建立了3维动力弹塑性分析模型; 采用“分解-叠加”法合成40组跨断层地震动,以多点激励的方式输入到建立的动力分析模型,进行非线性动力时程分析,研究了跨走滑断层多跨简支梁桥在地震动作用下的地震反应特征,分析了断层的穿越角度和穿越位置对跨走滑断层多跨简支梁桥地震响应的影响。结果表明:地震动作用下跨走滑断层桥梁结构会发生剧烈的位移反应; 断层穿越角度和穿越位置对桥梁地震反应有显著的影响; 地震动作用下跨断层简支梁桥的扭转效应不可忽视。

To investigate the seismic response of the multi-span simply supported girder bridge across the strike-slip fault,a 3-dimensional dynamic elastic-plastic analysis model is established for a 4-span simply supported girder bridge by using OpenSees.Forty sets of bidirectional ground motions across the fault are synthesized by the decomposition-incorporation method.These ground motions are then input into the model through multi-support excitation.A dynamic nonlinear time history analysis is carried out to investigate the seismic response of the multi-span simply supported girder bridge under the action of the ground motions across the strike-slip fault.In addition,the effects of the crossing angle and the crossing position of the multi-span simply supported girder bridge across a strike-slip fault on the bridge are analyzed.The results show that the bridge under the action of the ground motions across a strike-slip fault will experience a significant displacement response.Both the crossing angle and the crossing position have a significant effect on the seismic response of the bridge.Additionally,the torsion effect of the simply supported girder bridge under the action of the cross-fault ground motions should not be neglected.

引言
1 跨断层地震动模拟
2 多跨简支梁桥有限元模型
3 地震反应及损伤
4 参数分析
5 结论

图1 人工合成低频速度脉冲<br/>Fig.1 Artificially synthesized low-frequency velocity pulses

图1 人工合成低频速度脉冲
Fig.1 Artificially synthesized low-frequency velocity pulses

图2 合成地震动的位移时程曲线<br/>Fig.2 Displacement time history curve of synthetic ground motions

图2 合成地震动的位移时程曲线
Fig.2 Displacement time history curve of synthetic ground motions

图3 跨断层桥梁地震动输入转换方法示意图<br/>Fig.3 Diagram of input conversion method for cross-fault ground motions

图3 跨断层桥梁地震动输入转换方法示意图
Fig.3 Diagram of input conversion method for cross-fault ground motions

图4 背景桥梁工程概况
Fig.4 Background bridge engineering profile

图5 基于OpenSees有限元平台建立的桥梁三维数值模型<br/>Fig.5 Three-dimensional numerical modeling of background engineering bridges based on the OpenSees finite element platform

图5 基于OpenSees有限元平台建立的桥梁三维数值模型
Fig.5 Three-dimensional numerical modeling of background engineering bridges based on the OpenSees finite element platform

表1 根据位移延性系数定义的桥墩损伤状态<br/>Tab.1 Damage state of the pier defined by the displacement ductility ratio

表1 根据位移延性系数定义的桥墩损伤状态
Tab.1 Damage state of the pier defined by the displacement ductility ratio

图6 M=6.5、6.7和7.6时,各桥墩沿纵桥、横桥向墩顶位移峰值、位移延性系数(a、b)和位移时程(c、d)<br/>Fig.6 Peak displacements,displacement ductility ratio(a,b),and displacement time history(c,d)along the longitudinal and transverse bridge directions for pier tops hit by M6.5,M6.7,M7.6 earthquakes

图6 M=6.5、6.7和7.6时,各桥墩沿纵桥、横桥向墩顶位移峰值、位移延性系数(a、b)和位移时程(c、d)
Fig.6 Peak displacements,displacement ductility ratio(a,b),and displacement time history(c,d)along the longitudinal and transverse bridge directions for pier tops hit by M6.5,M6.7,M7.6 earthquakes

图7 不同震级下支座沿纵(a)、横(b)桥向的峰值位移均值和位移时程(c)<br/>Fig.7 Average of peak displacements along the longitudinal(a)and transverse(b)bridge directions and displacement time history(c)for bearings at different seismic magnitudes

图7 不同震级下支座沿纵(a)、横(b)桥向的峰值位移均值和位移时程(c)
Fig.7 Average of peak displacements along the longitudinal(a)and transverse(b)bridge directions and displacement time history(c)for bearings at different seismic magnitudes

图8 不同震级下主梁沿纵(a)、横(b)桥向的峰值位移和残余位移<br/>Fig.8 Peak and residual displacements along the longitudinal(a)and transverse(b)bridge directions for the ends of each girder at different earthquake magnitudes

图8 不同震级下主梁沿纵(a)、横(b)桥向的峰值位移和残余位移
Fig.8 Peak and residual displacements along the longitudinal(a)and transverse(b)bridge directions for the ends of each girder at different earthquake magnitudes

图9 墩底纵(a)、横(b)桥向最不利剪力随断层穿越角度的变化<br/>Fig.9 Variation of the unfavorable shear along the longitudinal(a)and transverse(b) bridge directions at the bottom of the pier with the fault crossing angle

图9 墩底纵(a)、横(b)桥向最不利剪力随断层穿越角度的变化
Fig.9 Variation of the unfavorable shear along the longitudinal(a)and transverse(b) bridge directions at the bottom of the pier with the fault crossing angle

图10 墩底纵(a)、横(b)向最不利弯矩和扭矩(c)随断层穿越角度的变化<br/>Fig.10 Variation of the unfavorable bending along the longitudinal(a)and transverse(b)and torsion moment at the bottom of the pier(c)bridge directions with the fault crossing angle

图10 墩底纵(a)、横(b)向最不利弯矩和扭矩(c)随断层穿越角度的变化
Fig.10 Variation of the unfavorable bending along the longitudinal(a)and transverse(b)and torsion moment at the bottom of the pier(c)bridge directions with the fault crossing angle

图11 主梁沿纵(a)、横(b)桥向的峰值位移和残余位移<br/>Fig.11 Displacement response of the girder along the longitudinal(a)and transverse(b)bridge directions

图11 主梁沿纵(a)、横(b)桥向的峰值位移和残余位移
Fig.11 Displacement response of the girder along the longitudinal(a)and transverse(b)bridge directions

图12 桥墩沿纵(a)、横(b)桥向的位移及位移延性系数<br/>Fig.12 Displacement and displacement ductility ratio of the pier along the longitudinal(a) and transverse(b)bridge directions

图12 桥墩沿纵(a)、横(b)桥向的位移及位移延性系数
Fig.12 Displacement and displacement ductility ratio of the pier along the longitudinal(a) and transverse(b)bridge directions