钢桁梁断面大幅后颤振结构和气动阻尼非线性特性风洞试验  

Wind Tunnel Tests Study on Nonlinear Characteristics of Structural and Aerodynamic Damping of Steel Truss Girder Section Under Large-amplitude Post-flutter

作　　者：韩艳 宋俊 李凯 胡朋 HAN Yan;SONG Jun;LI Kai;HU Peng(School of Civil Engineering,Changsha University of Science&Technology,Changsha 410114,Hunan,China)

机构地区：[1]长沙理工大学土木工程学院,湖南长沙410114

出　　处：《中国公路学报》2023年第7期56-66,共11页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52178451,51878080);湖南省自然科学基金项目(2020JJ3035,2021RC4031,2020JJ1006,2018JJ3538);湖南省研究生科研创新项目(CX20220886)。

摘　　要：通过大振幅的自由振动风洞试验,研究典型钢桁主梁断面节段模型单自由度扭转和两自由度竖向扭转系统的后颤振特性,量化结构和气动阻尼随振幅的非线性演化规律,并从该角度揭示钢桁主梁断面发生极限环颤振的机制;通过对比单自由度和两自由度系统的颤振行为,分析了竖向自由度对非线性极限环颤振的影响,并揭示其影响机制。此外,进一步探究了结构阻尼和弯扭频率比对非线性极限环颤振的影响。研究结果表明:结构阻尼和气动阻尼对振幅的依赖性是诱发非线性极限环颤振的主要原因;相对单自由度系统,竖向自由度的参与向两自由度系统引入了一个偏线性的竖向耦合气动负阻尼,会降低系统的稳定性,使得两自由度系统的颤振临界风速低于单自由度系统,同时也使得极限环颤振振幅大于单自由度系统,因此颤振分析中不可随意忽略竖向自由度;增加结构阻尼能够显著提升钢桁主梁断面的颤振临界风速,并降低后颤振极限环振动的振幅。Through high-amplitude free vibration wind tunnel tests,the post-flutter characteristics of single-degree-of-freedom torsion and two-degree-of-freedom vertical torsion system for a typical steel truss girder section model were studied.The nonlinear evolution laws of structural and aerodynamic damping with amplitude were quantified,and the mechanism of the steel truss girder section limit cycle flutter was revealed from this perspective.By comparing the flutter behavior of the single-degree-of-freedom and two-degree-of-freedom systems,the influence of the vertical degree of freedom on nonlinear limit cycle flutter was analyzed,and its influencing mechanism was revealed.In addition,the influence of structural damping and torsional-bending frequency ratio on nonlinear limit cycle flutter was also explored.The results showed that the dependence of structural and aerodynamic damping on amplitude was the main reason to induce nonlinear limit cycle flutter.Compared with the single-degree-of-freedom system,the participation of the vertical degree of freedom introduced a quasi-linear vertical coupling aerodynamic negative damping to the two-degree-of-freedom system,which reduced the stability of the system,resulting in a lower flutter critical wind speed of the two-degree-of-freedom system than the single degree-of-freedom system,and also resulted in a greater amplitude of limit cycle flutter than the single degree-of-freedom system.Therefore,the vertical degree of freedom should not be ignored in flutter analysis.Increasing structural damping can significantly increase the flutter critical wind speed of the steel truss girder section and reduce the amplitude of the post-flutter limit cycle vibration.

关 键 词：桥梁工程 后颤振 风洞试验 钢桁加劲梁 极限环振动 非线性阻尼 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]