大跨悬索桥结构阻尼的风速依赖特性研究  

The dependent relationship of modal damping on wind speed of long-span suspension bridges

作　　者：郭增伟[1,2] 时浩博 赵林 GUO Zeng-wei;SHI Hao-bo;ZHAO Lin(State Key Laboratory of Structural Dynamics for Bridge Engineering,Chongqing Communications Technology Research&Design Institute Co.LTD.,Chongqing 400067,China;State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通科研设计院有限公司桥梁工程结构动力学国家重点实验室,重庆400067 [2]重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室,重庆400074

出　　处：《振动工程学报》2022年第4期1001-1009,共9页Journal of Vibration Engineering

基　　金：国家自然科学基金资助项目(51878106);重庆市自然科学基金面上项目(cstc2019jcyj-msxmX0818);重庆市教委科学技术研究重点项目(KJZD-K202100704);桥梁工程结构动力学国家重点实验室开放基金(201501)联合资助。

摘　　要：针对大跨悬索桥的模态阻尼的风速依赖特性还未被深入探究的问题,以西堠门大桥健康监测系统获取的加劲梁加速度时程序列为分析对象,采用自然环境激励技术与特征系统实现算法相结合的方法(NExT‑ERA),识别了西堠门大桥在七组风速下共3015组模态频率和模态阻尼比,重点分析了结构模态阻尼比的风速依赖特征、概型分布及其置信区间,探讨了大跨悬索桥模态阻尼的统计参数随风速的变化规律。研究发现:不同风速下西堠门大桥横向振动阻尼比均在1.0%以上,但特定风速下结构竖向和扭转振动阻尼在95%保证率的最小值分别为0.2%和0.3%;风速的变化对大跨悬索桥模态阻尼比的大小和波动程度均会产生显著影响,相同风速条件下,结构扭转和横向模态阻尼的均值和方差均明显大于竖向阻尼;随着风速的增大,竖向阻尼的均值和方差逐渐增大,扭转阻尼的均值和方差略有减小,但横向阻尼变化不大;不同风速条件下结构3个方向的模态阻尼比均服从广义极值分布,但风速会影响结构竖向和扭转振型阻尼的概型分布的拖尾性质。In order to explore the dependent relationship of modal damping ratio on wind speed dependence of long-span suspension bridges,a total of 3015 sets of acceleration samples,which were gathered by the Xihoumen Bridge Health Monitoring System,were used to identify the modal parameters at 7 sets of wind speeds by the NExT-ERA method,which combined the natural environment excitation technology with feature system realization algorithm.The wind speed dependent characteristics,probability distribution and confidence interval of the structural modal damping ratios were analyzed.The statistics parameters of modal damping ratio and their variations with wind speed were also discussed.It has been found that although the mode damping in horizontal direction was always greater than 1.0%,the minimum value of damping ratio in vertical and torsional direction at 95%confidence level might approach to 0.2%and 0.3%respectively at a specific wind speed.Besides,the change of wind speed had a significant impact on the mean value and deviation of the modal damping ratio of long-span suspension bridges.Under the same wind speed,the mean value and variance of modal damping ratio in torsional and lateral direction were significantly greater than vertical damping ratio.As the wind speed increased,the mean value and variance of vertical damping ratios gradually increased,and the mean value and variance of the torsional damping ratios decreased slightly,while the lateral damping ratios did not change too much.The modal damping ratios of the three directions of the structure under different wind speeds all followed the generalized extreme value distribution,but the wind speed would affect the tailing properties of the probability distribution of the vertical and torsional mode damping ratios of structures.

关 键 词：大跨悬索桥 风速 现场实测 NExT‑ERA 模态阻尼比 

分 类 号：U441.3[建筑科学—桥梁与隧道工程] U448.25[交通运输工程—道路与铁道工程]