大跨拱桥三维多点随机地震响应分析
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摘要
对大跨度钢管混凝土拱桥进行三维正交地震动多点激励下的平稳随机响应分析。建立了跨径308m中承式钢管混凝土拱桥的精细有限元模型,采用多维多点平稳随机地震响应分析方法,数值仿真了该拱桥在一维P波、一维SH波、一维SV波多点激励下的地震响应以及考虑互谱的三维多点激励地震响应,研究了三维地震动、行波效应和部分相干效应对拱肋内力的影响。数值分析结果表明:考虑地震动的空间效应对拱肋内力有很大改变,地震动的行波效应对拱肋内力的影响比部分相干效应的影响更大,三维地震作用比单维地震作用的拱肋内力有较大增幅。对大跨度钢管混凝土拱桥,必须进行多维多点地震激励的响应分析,否则有可能严重低估结构的地震设计内力。
The random seismic analysis of long-span concrete filled steel-tube (CFST) arch bridge under multi-supports excitations of three-dimensional orthogonal earthquake motion was performed. The precise finite element model of a 308 m span half-through CFST arch bridge was established. The seismic response of the arch bridge under one-dimensional P-wave, one-dimensional SH-wave, one-dimensional SV-wave and three-dimensional earthquake excitations, considering cross-power spectrum of multi-supports, were numerically simulated by using the method of stationary random seismic analysis, and the influences of three-dimensional earthquake motion, traveling-wave effect and partial coherence effect on internal forces of arch rib were studied. The results show that the internal forces of arch rib may be greatly changed by considering the spatial variation of seismic motion. The traveling-wave effect of the earthquake motion on the internal forces of arch rib is greater than the partial coherence effect. The internal forces of arch rib under three-dimensional earthquake excitations are greater than that under one-dimensional excitation. The random seismic analysis under three-dimensional multi-supports earthquake excitations must be performed for the long-span CFST arch bridge, otherwise the seismic designed forces of the structure are likely to be underestimated seriously.
The random seismic analysis of long-span concrete filled steel-tube (CFST) arch bridge under multi-supports excitations of three-dimensional orthogonal earthquake motion was performed. The precise finite element model of a 308 m span half-through CFST arch bridge was established. The seismic response of the arch bridge under one-dimensional P-wave, one-dimensional SH-wave, one-dimensional SV-wave and three-dimensional earthquake excitations, considering cross-power spectrum of multi-supports, were numerically simulated by using the method of stationary random seismic analysis, and the influences of three-dimensional earthquake motion, traveling-wave effect and partial coherence effect on internal forces of arch rib were studied. The results show that the internal forces of arch rib may be greatly changed by considering the spatial variation of seismic motion. The traveling-wave effect of the earthquake motion on the internal forces of arch rib is greater than the partial coherence effect. The internal forces of arch rib under three-dimensional earthquake excitations are greater than that under one-dimensional excitation. The random seismic analysis under three-dimensional multi-supports earthquake excitations must be performed for the long-span CFST arch bridge, otherwise the seismic designed forces of the structure are likely to be underestimated seriously.
引文
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[2]Nazmy A D,Abdel-Ghaffar A M.Effects of ground motion spatial variability on the response of cable-stayed bridges[J].Earthquake Engineering and Structural Dynamics,1992,21(1):1-20.
[3]Ernesto H Z,Vanmarcke E H.Seismic random vibration a-nalysis of multi-support structural system[J].Journal of En-gineering Mechanics,ASCE,1994,120(5):1107-1128.
[4]Rassem M,Ghobarah A,Heidebrecht AC.Site effects on the seismic response of a suspension bridge[J].Engineering Structures,1996,18(5):363-370.
[5]Nicholas A,Alexander.Multi-support excitation of single span bridges,using real seismic ground motion recorded at the SMART-1array[J].Computers and Structures,2008,86(1):88-103.
[6]王君杰,王前信,江近仁.大跨拱桥在空间变化地震动下的响应[J].振动工程学报,1995,8(2):119-126.
[7]赵灿辉,周志祥.大跨度钢管混凝土拱桥在多维多点地震激励作用下的平稳随机响应[J].世界地震工程,2007,23(4):66-71.
[8]史志利,李忠献.随机地震动场多点激励下大跨度桥梁地震反应分析方法[J].地震工程与工程振动,2003,23(4):124-130.
[9]林家浩,张亚辉.随机振动的虚拟激励法[M].北京:科学出版社,2004.
[10]薛素铎,王雪生,曹资.空间网格结构多维多点随机地震响应分析的高效算法[J].世界地震工程,2004,20(3):43-49.
[11]Clough R W,Penzien J.Dynamics of structures[M].New York:McGraw-Hill,Inc.,1993.
[12]张翠红,吕令毅.大跨度斜拉桥在多点随机地震激励作用下的响应分析[J].东南大学学报(自然科学版),2004,34(2):249-252.
[13]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].地震学报,1996,18(1):55-62.
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