钢桁梁悬索桥抖振响应及其影响参数分析

钢桁梁是双层桥面悬索桥及峡谷地区悬索桥常用的加劲梁形式,该类加劲梁构件众多、阻风面积大,在脉动风荷载作用下的抖振响应非常显著。采用Davenport抖振频域方法对某钢桁梁悬索桥的顺风向、横风向及扭转方向的抖振响应进行分析。抖振有限元频域分析表明:抖振位移主要由加劲梁各方向的1阶振动模态控制,高阶模态的参与效应可以忽略;对于抖振加速度,高阶模态有较大贡献。进一步研究了定常及非定常自激气动力形式对气动阻尼的影响,结果表明准定常自激力描述竖向及侧向模态的气动阻尼具有足够的精度,但描述扭转模态的气动阻尼还存在很大的近似性。

Analysis of Buffeting Responses and Their Influential Parameters of Steel Truss Girder Suspension Bridge

The steel truss girder is a type of stiffening girder often used for double-deck suspension bridge and the suspension bridge built in valley region.The stiffening girder has lots of components in its section,considerable area of the components exposed to wind and the buffeting response of the girder under the action of plus wind is very significant.In this paper,the Davenport buffeting frequency domain method is used to analyze the buffeting responses along the wind and in the lateral wind and torsional directions for a steel truss girder suspension bridge.The results of the analysis show that the buffeting displacement is mainly governed by the first order vibration mode in all directions of the stiffening girder while the participation effect of the higher order vibration modes can be ignored.As for the buffeting acceleration,the contribution of the higher order vibration modes is great.The influences of the steady and non-steady self-excitation aerodynamic on the aerodynamic drag are studied for further details.The results of the study show that the aerodynamic drag of the vertical and lateral modes described by the quasi-steady self-excitation aerodynamic is sufficiently accurate,but the drag of the torsional mode described by the same is still quite approximate.