基于场地效应的山区高墩桥梁随机地震响应分析
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摘要
为研究场地效应对高墩桥梁随机地震响应的影响规律,基于随机振动理论,研究了不同墩高和墩高差时场地效应对山区高墩桥梁在强地震作用下多点激励随机响应规律。对基于ANSYS的随机振动计算理论进行推导并建立三维数值有限元模型,对不同墩高和墩高差的山区高墩桥梁进行不同场地条件下的多点激励随机地震分析。研究表明:场地效应对高墩桥梁地震响应影响显著。软场地条件下,桥墩位移和主梁轴力均较硬、中场地时大;随着墩高的增加,硬、中、软场地效应对主梁轴力影响先增大后减小;随着墩高差的增加,主梁轴力变化规律性不强,成波动性变化;主梁横桥向弯矩对场地效应敏感,软场地时响应是硬、中场地时的5～12倍,靠近高墩处的边跨反应比矮墩处边跨明显;随着墩高差的增加,软场地对主梁弯矩响应放大作用也随之增加。
In order to investigate the seismic response of high-rise pier bridge due to site effect,based on random vibration theory,random response of high-rise pier bridge in mountain area subjected to multi-point excitation of strong earthquake caused by local site effect with different pier heights(PH) and height differences between high pier and low pier(HDHL) was researched.The formula of ANSYS based random vibration theory was derived and the 3D finite element model was established.Such random response subjected to multi-point excitation under different case calculations,different local site effects,and different PHs and HDHLs,were conducted in detail.The result shows that(1) seismic response of high-rise pier bridge was affected significantly by local site effects,under soft ground condition,the pier displacement and the main beam axial force were larger than those under other ground conditions;(2) main beam axial force responses first increased and then decreased with the height increase of piers in hard,medium and soft ground effect;(3) main beam axial force response rules were not clear with HDHL increase,only fluctuated;(4) lateral moment of main beam was sensitive to local site effect,the response under soft ground condition was the 5-12 times larger than that under hard,medium ground conditions,the seismic response of side span near high pier was stronger than that of side span near low pier;(5) the amplification effect of main beam moment response due to soft ground condition increased with increase of HDHL.
In order to investigate the seismic response of high-rise pier bridge due to site effect,based on random vibration theory,random response of high-rise pier bridge in mountain area subjected to multi-point excitation of strong earthquake caused by local site effect with different pier heights(PH) and height differences between high pier and low pier(HDHL) was researched.The formula of ANSYS based random vibration theory was derived and the 3D finite element model was established.Such random response subjected to multi-point excitation under different case calculations,different local site effects,and different PHs and HDHLs,were conducted in detail.The result shows that(1) seismic response of high-rise pier bridge was affected significantly by local site effects,under soft ground condition,the pier displacement and the main beam axial force were larger than those under other ground conditions;(2) main beam axial force responses first increased and then decreased with the height increase of piers in hard,medium and soft ground effect;(3) main beam axial force response rules were not clear with HDHL increase,only fluctuated;(4) lateral moment of main beam was sensitive to local site effect,the response under soft ground condition was the 5-12 times larger than that under hard,medium ground conditions,the seismic response of side span near high pier was stronger than that of side span near low pier;(5) the amplification effect of main beam moment response due to soft ground condition increased with increase of HDHL.
引文
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[13]赵灿晖.大跨度桥梁地震响应分析中的非一致地震激励模型[J].西南交通大学学报,2002,37(3):236-240.ZHAO Canhui.The Asynchronous Excitation Model for the Seismic Response Analysis of Long-span Bridges[J].Journal of Southwest Jiaotong University,2002,37(3):236-240.
[14]AMIN M.Non-stationary Stochastic Model of Earthquake Motions[J].Earthquake Engineering Structural Dynamics,1968,94(7):109-115.
[15]LOH C H,YEH Y T.Spatial Variation and Stochastic Modeling of Seismic Differential Ground Movement[J].Earthquake Engineering and Structural Dynamics,1998,16(3):583-596.
[2]GIOVANNA Z,HONG Hao.Seismic Response of Multi-span Simply Supported Bridges to a Spatially Varying Earthquake Ground Motion[J].Earthquake Engineering and Structural Dynamics,2002,31(6):1325-1345.
[3]HAO Hong.Arch Responses to Correlated Multiple Excitations[J].Earthquake Engineering and Structural Dynamics,1993,22(5):389-404.
[4]LIN J H,ZHANG Y H.Seismic Spatial Effects for Long-span Bridges,Using the Pseudo Excitation Method[J].Engineering Structures,2004,26(9):1207-1216.
[5]武芳文,赵雷.考虑地震动局部场地效应的大跨度斜拉桥随机地震响应分析[J].地震研究,2010,33(1):93-98.WU Fangwen,ZHAO Lei.Stochastic Seismic Response of Long-span Cable-stayed Bridges under Local Site Effect[J].Journal of Seismological Research,2010,33(1):93-98.
[6]王新敏.ANSYS工程结构数值分析[M].北京:人民交通出版社,2007.WANG Xinmin.Numerical Analysis of Engineering Structure by ANSYS[M].Beijing:China Communications Press,2007.
[7]李永华,李思明.绝对位移直接求解的虚拟激励法[J].振动与冲击,2009,28(10):185-190.LI Yonghua,LI Siming.Pseudo Excitation Method Based on Solving Absolute Displacement[J].Journal of Vibration and Shock,2009,28(10):185-190.
[8]ANIL K CHOPRA.Dynamics of Structures(Theory and Applications to Earthquake Engineering)[M].California:University of California at Berkeley,2009.
[9]CLOUGH R W,PENZIEN J.Dynamics of Structures[M].3rd ed.USA:McGraw-Hill,1976.
[10]KIUREGHIAN A D,NEUENHOFER A.Response Spectrum Method for Multi-support Seismic Excitations[J].Earthquake Engineering and Structural Dynamics,1992,21(8):713-740.
[11]屈铁军,王君杰,王前信.空间变化的地震动功率谱的实用模型[J].地震学,1996,18(1):55-62.QU Tiejun,WANG Junjie,WANG Qianxin.Practical PSD Ground Motion Model with Spatial Effect[J].Journal ofEarthquake,1996,18(1):55-62.
[12]HOLMAN R H,HART G C.Structural Response to Segmental Non-stationary Random Excitation[J].The American Institute of Aeronautics and Astronautics,1972,19(4):1473-1478.
[13]赵灿晖.大跨度桥梁地震响应分析中的非一致地震激励模型[J].西南交通大学学报,2002,37(3):236-240.ZHAO Canhui.The Asynchronous Excitation Model for the Seismic Response Analysis of Long-span Bridges[J].Journal of Southwest Jiaotong University,2002,37(3):236-240.
[14]AMIN M.Non-stationary Stochastic Model of Earthquake Motions[J].Earthquake Engineering Structural Dynamics,1968,94(7):109-115.
[15]LOH C H,YEH Y T.Spatial Variation and Stochastic Modeling of Seismic Differential Ground Movement[J].Earthquake Engineering and Structural Dynamics,1998,16(3):583-596.
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