不同风场下不同桥梁节段模型的振动演化特征

Vibration evolution characteristics of bridge model with different sections and in different wind fields

以薄平板、闭口扁平箱梁和开槽扁平箱梁三种断面为研究对象进行小比例尺节段模型悬挂弹簧测振风洞实验,分析了紊流度和断面形式对桥梁振动演化特征和失稳风速的影响.研究结果表明:同一种桥梁断面在不同风场下的振动趋势是一致的,其位移响应均值和发散风不随紊流速度增加而增加;失稳风速从低到高依次为薄平板、闭口箱梁、开槽箱梁,而其失稳突发性从小到大顺序则刚好相反,薄平板和闭口箱梁发散时呈现出典型的硬颤振特征,而开槽箱梁发散时呈现出典型的软颤振特征.

Three kinds of bridge sections such as thin flat,closed flat box girder,and slotted flat box girder were taken as the objects to carry out the vibration measurement tests for their small scale section model with suspension spring system in wind tunnel.The influences of the turbulence intensities and the section types on the bridge vibration evolution characteristics and instability wind speeds were analyzed.The results show that the vibration evolution trends of the same kind of bridge section in different turbulent wind fields are consistent,the mean values of the displacement responses and the instability wind speeds don′t increase with the increase of turbulence.In the three types of cross sections,the instability wind speeds from low to high are as follows：thin plate,closed box girder,slotted box girder,and the order of burst of instability is just the opposite.Flat and closed flat box girder show the characteristics of the typical hard flutter in the divergence,however,slotted flat box girder shows the characteristic of the typical soft flutter in the divergence.