大攻角下超大跨度斜拉桥颤振性能节段模型风洞试验  

Flutter Performance of a Super-long-span Cable-stayed Bridge Under Large Attack Angles via Wind Tunnel Sectional Model Tests

作　　者：朱青[1,2,3] 陈文天 朱乐东[1,2,3] 崔译文 ZHU Qing;CHEN Wen-tian;ZHU Le-dong;CUI Yi-wen(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Bridge Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]同济大学桥梁工程系,上海200092 [3]同济大学桥梁结构抗风技术交通行业重点实验室,上海200092

出　　处：《中国公路学报》2019年第10期67-74,共8页China Journal of Highway and Transport

基　　金：国家自然科学基金重点项目(51938012);土木工程防灾国家重点实验室自主研究课题基金团队重点课题(SLDRCE15-A-03)

摘　　要：为了研究一座1400m跨径流线型闭口箱梁断面斜拉桥的颤振性能,根据其风致静力失稳或颤振前主梁最大有效风攻角已接近±10°的特点,通过弹簧悬挂节段模型试验,开展了大攻角下桥梁颤振性能研究。试验发现,在4°~10°风攻角下,高风速时模型均出现了弯扭耦合程度较弱的自限幅非线性颤振现象;而在其他攻角下,高风速时模型则表现为常规的发散型弯扭耦合颤振。研究发现,经典的线性颤振理论无法适用于研究试验中大攻角下出现的非线性颤振现象。因此,采用了一种简化的非线性半经验数学模型来表示非线性颤振中的自激扭矩,并从试验模型颤振位移时程中识别得到了模型参数。基于这一非线性自激力模型,通过试验测得的位移信号来构造自激扭矩时程,再利用自激扭矩的做功时程来识别各个气动参数。之后,利用其中的部分气动参数构造气动阻尼,并基于结构阻尼系数与气动线性阻尼系数之和为零的判断条件,提出了一种针对非线性颤振现象的临界风速确定方法,同时将线性和非线性颤振的起振判断条件进行了很好的统一。研究结果表明,利用这一方法求得的颤振临界风速与风洞试验中出现的现象基本吻合。Aeroelastic sectional model tests were performed to investigate the flutter performance of a super-long span cable-stayed bridge with a main span of 1 400 m and a closed box deck. Large attack angle tests were conducted as the estimated maximum effective attack angle of this bridge at critical wind speed could reach about ±10°. The test results show that nonlinear torsional flutter with self-limiting oscillations occurred at attack angles 4°-10°, whereas divergent bending-torsion flutter occurred at the other attack angles. As traditional flutter theory cannot be applied to the observed nonlinear flutter phenomenon, this study adopted a nonlinear semi-empirical mathematical model and identified the parameters of that model from the recorded displacement responses in the tests. A method is proposed to identify the critical wind speed for nonlinear flutter based on equivalent linear damping, which is the sum of structural damping and linear aerodynamic damping. Comparison with the test data shows that the proposed method can effectively estimate the critical flutter speed of the bridge.

关 键 词：桥梁工程 颤振临界风速 节段模型风洞试验 超大跨度斜拉桥 非线性自激力 大攻角 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]