以某主跨为1100m桁架加劲梁悬索桥为工程依托，采用弹性悬挂节段模型风洞试验方法，对桁架梁后颤振特征与机理进行研究。首先，对桁架梁节段模型试验系统的结构动力参数进行测试；然后，在不同风攻角下进行了桁架梁节段模型颤振试验研究；最后，从非线性阻尼角度对桁架梁节段模型极限环振动机理进行探讨。结果表明：在振幅较大时，桁架梁节段模型试验系统存在较为明显的阻尼非线性以及轻微的刚度非线性；在各试验攻角下,桁架梁节段模型后颤振现象均表现为极限环振动，风攻角对颤振临界风速与振幅随风速增长的斜率均有显著影响；桁架梁节段模型极限环振动具有弯扭耦合特性，并且弯扭耦合程度随振幅增大而增强；对于桁架梁节段模型试验，结构阻尼非线性是极限环振动限幅的有利因素，而气动阻尼非线性在不同风攻角下作用效果不同。
Abstract
A truss stiffening girder suspension bridge with a main span of 1100m was taken as the engineering background. The wind tunnel tests of the spring-suspend section model were conducted to study the characteristics and mechanism of the post flutter. First, the structural parameters of the section model test system with the truss girder were tested. Then, the flutter tests of the truss girder section model were carried out at different wind attack angles. Finally, the mechanism of limit cycle oscillation (LCO) for the truss girder section model was discussed in the view of nonlinear damping. The results show that there are obvious damping nonlinearity and slight stiffness in the section model test system with the truss girder at large amplitudes. The LCO of the truss girder section model is observed at each wind attack angle. Wind attack angle has significant effects on the critical flutter wind speed and the slopes of the amplitude versus wind speed. The LCO of the truss girder section model is characterized by a coupled bending and torsion vibration, and the bending-torsion coupling level increases as the amplitude increases. For the wind tunnel tests of the truss girder section model, structural damping nonlinearity is a favorable factor for the stability of LCO, while aerodynamic damping nonlinearity has different effects at different wind attack angles.
关键词
悬索桥 /
桁架加劲梁 /
后颤振 /
非线性阻尼 /
风洞试验
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Key words
suspension bridge /
truss stiffening girder /
post flutter /
nonlinear damping /
wind tunnel test
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