SH波入射下河谷地形对连续刚构桥地震反应影响
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摘要
根据显式有限元方法采用人工透射边界,设置不同入射角度,对一河谷地形进行二维场地地震反应数值模拟,分析SH波入射下河谷地形的地震动分布特征;以场地地震反应分析结果作为各桥墩的地震动输入,分析连续刚构桥地震反应的特点。结果表明:SH波入射下河谷地形各点的地震动分布存在明显的差异;入射方向是影响河谷地震动分布的重要因素;斜入射情形下,河谷各点的位移差动明显增大。考虑河谷地形影响后,刚构桥地震反应存在显著差异,但难以找到一致规律性。一致激励不能代表最不利地震作用情况,地形因素和入射方向对结构内力反应具有重大影响,大跨度桥梁抗震分析与设计应予以充分考虑。
Using explicit finite element method with artificial transmitting boundary,the seismic response of a canyon is analyzed under incident SH waves with the assumption of different angles of incidence.The distribution features of ground motion parameters,which include peak ground acceleration(PGA),peak relative ground deformation(PRGD)and acceleration response spectrum,are summarized.The ground motions are used as excitations of a continuous frame bridge with the improved Large Mass Method.It indicates that canyon topography has significant influences on the surface ground motions in terms of the angle of incidence.The ground surface has been characterized by larger deformations in the case of oblique incident waves.It is also concluded that it's hard to find out any regularity of structural seismic responses considering the canyon topography effects under incident SH waves.In general,the canyon topography should be a carefully considered factor in structural seismic response analysis and aseismic design.
Using explicit finite element method with artificial transmitting boundary,the seismic response of a canyon is analyzed under incident SH waves with the assumption of different angles of incidence.The distribution features of ground motion parameters,which include peak ground acceleration(PGA),peak relative ground deformation(PRGD)and acceleration response spectrum,are summarized.The ground motions are used as excitations of a continuous frame bridge with the improved Large Mass Method.It indicates that canyon topography has significant influences on the surface ground motions in terms of the angle of incidence.The ground surface has been characterized by larger deformations in the case of oblique incident waves.It is also concluded that it's hard to find out any regularity of structural seismic responses considering the canyon topography effects under incident SH waves.In general,the canyon topography should be a carefully considered factor in structural seismic response analysis and aseismic design.
引文
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[2]周国良.河谷地形对多支撑大跨桥梁地震反应影响[D].北京:中国地震局工程力学研究所,2010(Zhou Guoliang.Canyon topography effects on seismic responses of multiply-supported bridges[D].Beijing:Institute of Engineering Mechanics,China Earthquake Administration,2010(in Chinese))
[3]Wong HL,Jennings P C.Effects of canyon topography on strong ground motion[J].Bulletin of the Seismological Society of America,1975,65(5):1239-1257
[4]Trifunac MD.Surface Motion of a semi-cylindrical alluvial valley for incident plane SH waves[J].Bulletin of the Seismological Society of America,1971,61(6):1755-1770
[5]Lee S J,Komatitsch D,Huang B S,et al.Effects of topography on seismic-wave propagation:an example from northern Taiwan[J].Bulletin of the Seismological Society of America,2009,99(1):314-325
[6]Zhou Guoliang,Li Xiaojun,Qi Xingjun.Seismic response analysis of continuous rigid frame bridge considering canyon topography effects under incident SV waves[J].Earthquake Science,2010,23(1):53-61
[7]廖振鹏.工程波动理论导论[M].第二版.北京:科学出版,2002(Liao Zhenpeng.Introduction to wave motion theories for engineering[M].Second Edition.Beijing:Science Press,2002(in Chinese)
[8]李小军.非线性场地地震反应分析方法研究[D].北京:中国地震局工程力学研究所,1993(Li Xiaojun.Study on the method for analyzing the earthquake response of nonlinear site[D].Beijing:Institute of Engineering Mechanics,China Earthquake Administration,1993(in Chinese))
[9]Leger P,Ide I M,Paultre P.Multiple Support seismic analysis of large structures[J].Computers&Structures,1990,36(6):1153-1158
[10]黄小国,胡大琳,张后举.行波效应对大跨度连续刚构桥地震反应的影响[J].长安大学学报,2008,28(1):72-76(Huang Xiaoguo,Hu Dalin,Zhang Houju.Effects of traveling wave to seismic response of long span rigid-framed bridge[J].Journal of Chang an University:Natural Science Edition,2008,28(1):72-76(in Chinese))
[11]周国良,李小军,喻畑,等.结构地震作用的基底激励模型及其适用性[J].建筑结构学报,2010,31(增2):82-88(Zhou Guoliang,Li Xiaojun,Tian Yu,et al.Applicability research on base excitation models used in structural seismic response analysis[J].Journal of Building Structures,2010,31(S2):82-88(in Chinese))
[12]李山有,马强,武东坡,等.断层场地地震反应特征研究[J].地震工程与工程振动,2003,23(5):32-37(Li Shanyou,Ma Qiang,Wu Dongpo,et al.Study on characteristics of seismic responses of fault site[J].Earthquake Engineering&Engineering Vibration,2003,23(5):32-37(in Chinese))
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