多点激励下大跨度连续刚构桥地震响应振动台阵试验研究
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摘要
目前对于大跨度桥梁在多维多点激励下的地震响应尚缺乏试验研究。以一高墩大跨度钢筋混凝土连续刚构桥工程为对象,按1/10比例设计和制作一座三跨刚构桥模型,并通过地震模拟振动台阵试验,研究一致激励、行波激励和局部场地效应等对刚构桥地震响应的影响。研究表明:刚构桥对地震动的频谱特性十分敏感,地震响应差异较大;行波效应增大桥墩变形和墩底应变,其影响程度随视波速和墩梁约束的不同而有差异,且桥墩墩底较墩梁固结处对行波效应更为敏感;局部场地效应增大桥墩变形和墩底应变,且其对中墩和边墩以及墩底和墩梁固结处的影响有所不同;同时考虑行波效应和局部场地效应,桥墩的动力响应较一致激励以及单独考虑行波效应和局部场地效应时有所增大。因此,在长大桥梁地震响应精细化分析中必须考虑地震动空间效应。
Up to now,rare experimental researches focus on the seismic response of long-span bridges under multi-support earthquake excitation.A 1∶ 10 three-span continuous rigid framed bridge model is designed according to a practical long-span reinforced concrete bridge with high piers in order to carry out the corresponding shaking table tests.The uniform excitation,traveling wave effect,local site effect and the combination of the above two effects are considered in the experiment.The experimental results indicate that the continuous rigid framed bridge is sensitive to the spectrum characteristics of the ground motions,and the seismic responses show great difference in various earthquake excitations.When the surface wave velocity is lower,the deformation of the pier and the strain at the bottom of the pier increase under the traveling wave excitation.The effect varies with the surface wave velocity and the constraint condition types,and the bottom of the pier is more sensitive to the traveling wave effect.If the local site effect is considered,the deformation of the pier and the strain at the bottom of the pier also increase,and the effect is different for the positions such as the middle-pier,the abutment,the bottom of the pier and the connections.When the traveling wave effect and local site effect is considered simultaneously,the dynamic responses of the pier are bigger than those under uniform excitation,solo action of the traveling wave effect or local site effect.Therefore,it is important to consider the effects of spatial variation of ground motion for the long-span bridges seismic analysis.
Up to now,rare experimental researches focus on the seismic response of long-span bridges under multi-support earthquake excitation.A 1∶ 10 three-span continuous rigid framed bridge model is designed according to a practical long-span reinforced concrete bridge with high piers in order to carry out the corresponding shaking table tests.The uniform excitation,traveling wave effect,local site effect and the combination of the above two effects are considered in the experiment.The experimental results indicate that the continuous rigid framed bridge is sensitive to the spectrum characteristics of the ground motions,and the seismic responses show great difference in various earthquake excitations.When the surface wave velocity is lower,the deformation of the pier and the strain at the bottom of the pier increase under the traveling wave excitation.The effect varies with the surface wave velocity and the constraint condition types,and the bottom of the pier is more sensitive to the traveling wave effect.If the local site effect is considered,the deformation of the pier and the strain at the bottom of the pier also increase,and the effect is different for the positions such as the middle-pier,the abutment,the bottom of the pier and the connections.When the traveling wave effect and local site effect is considered simultaneously,the dynamic responses of the pier are bigger than those under uniform excitation,solo action of the traveling wave effect or local site effect.Therefore,it is important to consider the effects of spatial variation of ground motion for the long-span bridges seismic analysis.
引文
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[12]王蕾,赵成刚,王智峰.考虑地形影响和多点激励的大跨高墩桥地震响应分析[J].土木工程学报,2006,39(1):50-53,59(Wang Lei,Zhao Chenggang,WangZhifeng.Seismic responses analysis of continuous rigid-framed bridge with hige piers considering topographiceffects and multi-support excitations[J].China CivilEngineering Journal,2006,39(1):50-53,59(in Chinese))
[13]李忠献.工程结构试验理论与技术[M].天津:天津大学出版社,2004(Li Zhongxian.Theory and technique ofengineering structure experiments[M].Tianjin:TianjinUniversity Press,2004(in Chinese))
[14]章关永.桥梁结构试验[M].北京:人民交通出版社,2002
[15]屈铁军,王君杰.空间变化的地震动功率谱的实用模型[J].地震学报,1996,18(1):55-62
[2]钟万勰,林家浩,吴志刚,等.大跨度桥梁分析方法的一些进展[J].大连理工大学学报,2000,40(2):127-135(Zhong Wanxie,Lin Jiahao,Wu Zhigang,et al.Development of analytical method for long-span bridges[J].Journal of Dalian University of Technology,2000,40(2):127-135(in Chinese))
[3]Bogdanoff J L,Goldberg J E,Schiff A J.The effect ofground transmission time on the response of long structures[J].Bulletin of the Seismological Society of America,1965,55(3):627-640
[4]Hao H.Stability of simple beam subjected to multipleseismic excitations[J].Journal of Engineering Mechanics,1997,123(7):739-742
[5]Harichandran R S,Hawwari A,Sweidan B N.Response oflong-span bridges to spatially varying ground motion[J].Journal of Structural Engineering,1996,122(5):476-484
[6]Soyluk K.Comparison of random vibration methods formulti-support seismic excitation analysis of long-spanbridges[J].Engineering Structures,2004,26(11):1573-1583
[7]Zanardo G,Hao H,Modena C.Seismic response of multi-span simply supported bridges to a spatially varyingearthquake ground motion[J].Earthquake Engineering&Structural Dynamics,2002,31(6):1325-1345
[8]Nuti C,Vanzi I.Influence of earthquake spatial variabilityon differential soil displacements and SDF system response[J].Earthquake Engineering&Structural Dynamics,2005,34(11):1353-1374
[9]Lou L,Zerva A.Effects of spatially variable ground motionson the seismic response of a skewed,multi-span,RC highwaybridge[J].Soil Dynamics and Earthquake Engineering,2005,25(7):729-740
[10]Lupoi A,Franchin P,Pintop E,et al.Seismic design ofbridges accounting for spatial variability of ground motion[J].Earthquake Engineering&Structural Dynamics,2005,34(4/5):327-348
[11]李忠献,史志利.行波激励下大跨度连续刚构桥的地震反应分析[J].地震工程与工程振动,2003,23(2):68-76(Li Zhongxian,Shi Zhili.Seismic response analysis forlong-span continuous rigid-framed bridges under excitationof traveling waves[J].Earthquake Engineering andEngineering Vibration,2003,23(2):68-76(in Chinese))
[12]王蕾,赵成刚,王智峰.考虑地形影响和多点激励的大跨高墩桥地震响应分析[J].土木工程学报,2006,39(1):50-53,59(Wang Lei,Zhao Chenggang,WangZhifeng.Seismic responses analysis of continuous rigid-framed bridge with hige piers considering topographiceffects and multi-support excitations[J].China CivilEngineering Journal,2006,39(1):50-53,59(in Chinese))
[13]李忠献.工程结构试验理论与技术[M].天津:天津大学出版社,2004(Li Zhongxian.Theory and technique ofengineering structure experiments[M].Tianjin:TianjinUniversity Press,2004(in Chinese))
[14]章关永.桥梁结构试验[M].北京:人民交通出版社,2002
[15]屈铁军,王君杰.空间变化的地震动功率谱的实用模型[J].地震学报,1996,18(1):55-62
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