碰撞对高铁简支桥梁横向地震响应影响的振动台试验研究
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摘要
地震所导致的碰撞是影响桥梁结构地震响应的一个重要因素。该文以32 m标准跨径高铁简支梁桥为研究对象,按1/6缩尺比设计及制作了单跨桥梁振动台试验模型,并针对以往点-面接触碰撞测力装置不能真实反映原型结构碰撞接触形式的不足,设计了一种新型面-面接触的碰撞测力装置。通过振动台试验研究了桥梁模型在地震激励下的横向碰撞效应,并通过快速傅里叶变换(FFT)从频域角度分析了碰撞对桥梁结构横向地震响应的影响。结果表明:新型测力装置能够较为准确地测得挡块与垫石之间的碰撞力时程;挡块与垫石间的碰撞限制了墩梁间的横向相对位移的发展,但会放大桥墩墩底弯矩响应和梁体加速度响应。在不考虑挡块时,桥梁结构的地震响应功率谱在低频区(结构基频附近)具有较高的幅值,即地震响应主要受结构基频控制;而在设置挡块后,碰撞改变了地震响应的频率分布,在高频区的功率谱幅值明显增大。
Earthquake-induced pounding is a critical factor affecting seismic responses of bridges. A high-speed railway simply-supported girder bridge with a standard span of 32 m was studied. A single-span bridge model was designed and manufactured at a scale of 1/6. A new surface-surface contact device for measuring the pounding force was proposed to overcome the shortcoming of previous point-surface devices that cannot model the actual contact form of the structures. A series of shake-table tests were conducted to investigate the transverse pounding effect of the bridge model, and the influence of the pounding on transverse seismic responses of the bridge was analyzed in the frequency domain by the fast Fourier transform(FFT). The results showed that: 1) the new force measuring device could accurately measure the time history of the pounding force; 2) the pounding between the shear keys and the bearing bases restricted the development of the relative transverse displacement between the superstructure and the substructure, but it amplified the girder acceleration and the bending moment near the base of the pier; 3) when the shear keys were not installed, the power spectra of the seismic responses had higher amplitudes in the low-frequency region(near the fundamental frequency of the bridge model), i.e. the seismic responses were dominated by the fundamental frequency of the structure when the pounding was not considered.However, after the shear keys were installed, the pounding altered the frequency content of the seismic responses,and the amplitudes of power spectra were increased significantly in the high-frequency region.
Earthquake-induced pounding is a critical factor affecting seismic responses of bridges. A high-speed railway simply-supported girder bridge with a standard span of 32 m was studied. A single-span bridge model was designed and manufactured at a scale of 1/6. A new surface-surface contact device for measuring the pounding force was proposed to overcome the shortcoming of previous point-surface devices that cannot model the actual contact form of the structures. A series of shake-table tests were conducted to investigate the transverse pounding effect of the bridge model, and the influence of the pounding on transverse seismic responses of the bridge was analyzed in the frequency domain by the fast Fourier transform(FFT). The results showed that: 1) the new force measuring device could accurately measure the time history of the pounding force; 2) the pounding between the shear keys and the bearing bases restricted the development of the relative transverse displacement between the superstructure and the substructure, but it amplified the girder acceleration and the bending moment near the base of the pier; 3) when the shear keys were not installed, the power spectra of the seismic responses had higher amplitudes in the low-frequency region(near the fundamental frequency of the bridge model), i.e. the seismic responses were dominated by the fundamental frequency of the structure when the pounding was not considered.However, after the shear keys were installed, the pounding altered the frequency content of the seismic responses,and the amplitudes of power spectra were increased significantly in the high-frequency region.
引文
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[16]Li J Z,Xiang N,Tang H,et al.Shake-table tests and numerical simulation of an innovative isolation system for highway bridges[J].Soil Dynamics&Earthquake Engineering,2016,86:55―70.
[17]叶爱君,方家欣,张少为,等.小箱梁桥横向减震体系及其耗能特性[J].中国公路学报,2017,30(12):21―29.Ye Aijun,Fang Jiaxing,Zhang Shaowei,et al.Transverse seismic system of multi-box girder bridges and its energy dissipation characteristics[J].China Journal of Highway&Transport,2017,30(12):21―29.(in Chinese)
[18]Kun C,Jiang L,Chouw N.Influence of pounding and skew angle on seismic response of bridges[J].Engineering Structures,2017,148:890―906.
[19]Masroor A,Mosqueda G.Experimental simulation of base-isolated buildings pounding against moat wall and effects on superstructure response[J].Earthquake Engineering&Structural Dynamics,2012,41(14):2093―2109.
[20]许祥,刘伟庆,徐秀丽.结构地震碰撞分析的线性粘弹性碰撞模型[J].工程力学,2013,30(2):278-284.Xu Xiang,Liu Weiqing,Xu Xiuli.Linear viscoelastic model of earthquake induced structural pounding[J].Engineering Mechanics,2013,30(2):278―284.(in Chinese)
[21]禚一,李忠献,王菲.桥梁地震碰撞分析中不同接触单元模型的对比分析[J].工程力学,2014,31(3):11―17.Zhuo Yi,Li Zhongxian,Wang Fei.Comparative analysis of different contact element models in seismic pounding analysis of bridges[J].Engineering Mechanics,2014,31(3):11―17.(in Chinese)
[2]贾宏宇,杜修力,李晰,等.地震作用下高墩铁路桥梁梁体碰撞间隙宽度需求机理分析[J].工程力学,2017,34(2):207―215.Jia Hongyu,Du Xiuli,Li Xi,et al.Demand mechanism analysis on pounding separation distance of high pier railway subjected to earthquake excitations[J].Engineering Mechanics,2017,34(2):207―215.(in Chinese)
[3]沙奔,王浩,陶天友,等.考虑混凝土损伤的隔震连续梁桥碰撞响应分析[J].工程力学,2018,35(3):193―199.Sha Ben,Wang Hao,Tao Tianyou,et al.Analysis on pounding responses of isolated continuous girder bridge considering concrete damage[J].Engineering Mechanics,2018,35(3):193―199.(in Chinese)
[4]李青宁,尹俊红,张瑞杰,等.桥梁碰撞振动台试验及参数敏感性分析[J].长安大学学报(自然科学版),2016,36(4):58―65.Li Qingning,Yin Junhong,Zhang Ruijie,et al.Shaking table test of bridge pounding and analysis on parameter sensitivity[J].Journal of Chang’an University(Natural Science Edition),2016,36(4):58―65.(in Chinese)
[5]李忠献,张勇,岳福青.地震作用下隔震简支梁桥碰撞反应的振动台试验[J].地震工程与工程振动,2007,27(2):152―157.Li Zhongxian,Zhang Yong,Yue Fuqing.Shaking table test on pounding responses of simply supported isolated bridges under earthquake excitation[J].Journal of Earthquake Engineering&Engineering Vibration,2007,27(2):152―157.(in Chinese)
[6]Guo A X,Li Z J,Li H,et al.Experimental and analytical study on pounding reduction of base‐isolated highway bridges using MR dampers[J].Earthquake Engineering&Structural Dynamics,2009,38(11):1307―1333.
[7]Guo A X,Li Z J,Li H.Point-to-surface pounding of highway bridges with deck rotation subjected to bi-directional earthquake excitations[J].Journal of Earthquake Engineering,2011,15(2):274―302.
[8]Goel R K,Chopra A K.Role of shear keys in seismic behavior of bridges crossing fault-rupture zones[J].Journal of Bridge Engineering,2008,13(4):398―408.
[9]Bi K,Hao H.Modelling of shear keys in bridge structures under seismic loads[J].Soil Dynamics&Earthquake Engineering,2015,74:56―68.
[10]Maleki S.Seismic modeling of skewed bridges with elastomeric bearings and side retainers[J].Journal of Bridge Engineering,2005,10(4):442―449.
[11]Liu C,Gao R.Design method for steel restrainer bars on railway bridges subjected to spatially varying earthquakes[J].Engineering Structures,2018,159:198―212.
[12]杨孟刚,孟栋梁,戴良缘.考虑轨道约束的高铁简支梁桥横向地震碰撞效应[J].中南大学学报(自然科学版),2018,49(4):916―924.Yang Menggang,Meng Dongliang,Dai Liangyuan.Transverse seismic pounding effect for simply-supported girder bridges of high-speed railway considering track constraint[J].Journal of Central South University(Science and Technology),2018,49(4):916―924.(in Chinese)
[13]Bozorgzadeh A,Megally S,Restrepo J I,et al.Capacity evaluation of exterior sacrificial shear keys of bridge abutments[J].Journal of Bridge Engineering,2006,11(5):555―565.
[14]Han Q,Zhou Y L,Ou Y,et al.Seismic behavior of reinforced concrete sacrificial exterior shear keys of highway bridges[J].Engineering Structures,2017,139:59―70
[15]项乃亮,李建中.不同挡块形式对中小跨径梁桥横向抗震性能的影响[J].工程力学,2016,33(3):188―195.Xiang Nailiang,Li Jianzhong.Effect of different types of retainers on transverse seismic performance of small and mid-span girder bridges[J].Engineering Mechanics,2016,33(3):188―195.(in Chinese)
[16]Li J Z,Xiang N,Tang H,et al.Shake-table tests and numerical simulation of an innovative isolation system for highway bridges[J].Soil Dynamics&Earthquake Engineering,2016,86:55―70.
[17]叶爱君,方家欣,张少为,等.小箱梁桥横向减震体系及其耗能特性[J].中国公路学报,2017,30(12):21―29.Ye Aijun,Fang Jiaxing,Zhang Shaowei,et al.Transverse seismic system of multi-box girder bridges and its energy dissipation characteristics[J].China Journal of Highway&Transport,2017,30(12):21―29.(in Chinese)
[18]Kun C,Jiang L,Chouw N.Influence of pounding and skew angle on seismic response of bridges[J].Engineering Structures,2017,148:890―906.
[19]Masroor A,Mosqueda G.Experimental simulation of base-isolated buildings pounding against moat wall and effects on superstructure response[J].Earthquake Engineering&Structural Dynamics,2012,41(14):2093―2109.
[20]许祥,刘伟庆,徐秀丽.结构地震碰撞分析的线性粘弹性碰撞模型[J].工程力学,2013,30(2):278-284.Xu Xiang,Liu Weiqing,Xu Xiuli.Linear viscoelastic model of earthquake induced structural pounding[J].Engineering Mechanics,2013,30(2):278―284.(in Chinese)
[21]禚一,李忠献,王菲.桥梁地震碰撞分析中不同接触单元模型的对比分析[J].工程力学,2014,31(3):11―17.Zhuo Yi,Li Zhongxian,Wang Fei.Comparative analysis of different contact element models in seismic pounding analysis of bridges[J].Engineering Mechanics,2014,31(3):11―17.(in Chinese)