悬索桥并列双吊索整体风振特性与气动阻尼研究

通过并列耦合双吊索节段模型的整体测振与测力风洞试验,研究不同间距下双吊索的整体振动行为与气动阻尼特性。引入驰振气动阻尼非线性项的动力方程模型,得到非线性振动的近似解析方法。基于弹性悬挂节段模型动力响应识别出驰振非线性气动参数,并与经典单自由度驰振理论结果进行对比分析。研究结果表明:并列耦合双吊索在一定工况下会发生剧烈的整体尾流致振现象,结构阻尼比对其起振风速影响明显;经典驰振理论求得的气动负阻尼绝对值要小于识别得到的气动负阻尼绝对值,横、顺风向两自由度耦合失稳较单自由度驰振更易发生。

Aerodynamic damping and wind-induced vibrations for coupled parallel twin hangers of suspension bridges

The wind tunnel tests were carried out to investigate the wind-induced vibration and aerodynamic damping on coupled twin cylinders at various cylinder spacing. The dynamic equation model for galloping incorporating the nonlinear term of aerodynamic damping was introduced, and the nonlinear aerodynamic parameters of galloping was evaluated from the dynamic response of elastically mounted section model. The large-amplitude vibration of coupled twin cylinders was observed for certain cylinder spacing, and the structural damping ratio had a significant effect on the vibration wind speed. Results show that the identified value of negative aerodynamic damping from dynamic response is obviously larger than that evaluated from the classical galloping theory. This indicates that the coupled 2 DOF wake-induced instability are more likely to occur than single degree of freedom galloping.