大跨度悬索桥抖振时变动力可靠性分析
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摘要
随着大跨度悬索桥跨径的日益增大,结构趋于轻柔,阻尼减小,对风的作用更加敏感,风作用下桥梁结构的安全性已成为人们极为关注的重要问题。在桥梁抖振时程分析基础上,模拟出脉动风作用下东海某跨海悬索桥主梁节点的位移响应时程并通过傅立叶变换得到其功率谱,采用基于首次超越的Poisson过程法,分析其抖振动力可靠度,并探讨了结构抗力的随机性以及时变性对动力可靠度的影响。结果表明考虑结构抗力的随机性会使得动力可靠度降低,结构抗力在使用期限内的衰减对平均风60 m/s强风作用时可靠度的影响是显著的,而40 m/s平均风速时影响不大,由于当地百年一遇的基准风速为41.12 m/s,因此可认为结构在运营期间的抖振动力可靠性能够满足要求。
With the span of long-span suspension bridge increases,structures become flexible,damping decreases,structures are more sensitive to the wind action,and the structural safety of the bridge under strong wind has become an important issue of great concern.Based on the accurate bridge buffeting analysis of time history,the time history of displacements of a suspension bridge girder are simulated,then their power spectrums can be got by fourier transform.The dynamic reliability of buffeting responses is researched by Poisson process method based on the first excursion mechanism,also the effects of randomness and timedependence of structural resistance are discussed.The results show that the randomness of structural resistance will reduce the dynamic reliability,the reduction of bridge structural resistance have a significant impact to the dynamic reliability when the mean wind is 60 m/s,while the 40 m/s wind speed,it has a little effect,as the maximum of local winds for hundred years is 41.12 m/s,so the structure can be considered safe to the wind dynamic reliability.
With the span of long-span suspension bridge increases,structures become flexible,damping decreases,structures are more sensitive to the wind action,and the structural safety of the bridge under strong wind has become an important issue of great concern.Based on the accurate bridge buffeting analysis of time history,the time history of displacements of a suspension bridge girder are simulated,then their power spectrums can be got by fourier transform.The dynamic reliability of buffeting responses is researched by Poisson process method based on the first excursion mechanism,also the effects of randomness and timedependence of structural resistance are discussed.The results show that the randomness of structural resistance will reduce the dynamic reliability,the reduction of bridge structural resistance have a significant impact to the dynamic reliability when the mean wind is 60 m/s,while the 40 m/s wind speed,it has a little effect,as the maximum of local winds for hundred years is 41.12 m/s,so the structure can be considered safe to the wind dynamic reliability.
引文
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[10]SU Cheng,FAN Xue-ming,HE Tao.Wind-induced Vibration Analysis of a Cable-stayed Bridge During Erection by a Modi-fied Time-domain Method[J].Journal of Sound and Vibration,2007,303(2):330-342.
[11]韩燕,陈政清,罗延忠.双肢薄壁墩连续刚构桥平衡悬臂施工阶段的抖振时域分析[J].中国公路学报,2008(1):59-64.
[2]项海帆.现代桥梁抗风理论与实践[M].北京:人民交通出版社,2005.
[3]李桂青,曹宏,李秋胜,等.结构动力可靠性理论及其应用[M].北京:地震出版社,1993.
[4]欧进萍,段宇博.结构抗风可靠性分析与设计的等效随机静风荷载[J].建筑结构,1995,7(4):27-42.
[5]李桂青,曹宏.高耸结构在风荷载作用下的动力可靠性分析[J].土木工程学报,1987,20(1):57-64.
[6]黄耀怡.大跨度悬索桥塔的空气动力可靠性分析[J].华东公路,1994(6):3-12.
[7]卢伟,强士中,李晓渝.斜拉桥抖振动力可靠性分析[J].振动与冲击,2001,20(2):82-85.
[8]刘高,林家浩,王秀伟.基于首超破坏机制的大跨度斜拉桥抖振动力可靠性分析[J].应用力学学报,2004,21(3):53-57.
[9]Namini A.Analytical Modeling of Flutter Derivatives as Finite Elements[J].Computers&Structures,1991,41(5):1055-1064.
[10]SU Cheng,FAN Xue-ming,HE Tao.Wind-induced Vibration Analysis of a Cable-stayed Bridge During Erection by a Modi-fied Time-domain Method[J].Journal of Sound and Vibration,2007,303(2):330-342.
[11]韩燕,陈政清,罗延忠.双肢薄壁墩连续刚构桥平衡悬臂施工阶段的抖振时域分析[J].中国公路学报,2008(1):59-64.
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