风攻角对分离双扁平箱梁涡振特性的影响

Effect of Wind Attacking Angle on Vortex Induced Vibration Characteristics of Twin Separate Flat Box Girders

在均匀流场中进行了分离双扁平箱梁涡激振动节段模型风洞试验,研究了-5°^+5°间8个不同风攻角下分离双箱梁在D/B=0.1(D为双箱梁的净间距,B为单箱梁的宽度)时的涡振特性,并将结果与单箱梁的结果进行了对比。结果显示:+5°风攻角下,上下游箱梁的涡激振动受到了抑制,表现为振幅的减小和风速锁定区间的缩短;随着风攻角的逐渐变小,这种抑制效应逐渐变弱,并转变为放大效应;+2°风攻角下,单箱梁未发生涡激振动现象,但上下游箱梁均发生了比较明显的涡激振动。

Sectional model wind tunnel tests are carried out in the uniform flow field for twin separate flat box girders under D/B=0.1(Dis net distance of twin separate flat box girders and Bis width of single flat box girder)and wind attacking angle ranging from-5°to+5°.Vortex induced vibration characteristics of twin separate flat box girders are studied and compared with that of single box girder.The results show that when the wind attacking angle is +5°,the vibration amplitude and wind speed range of both upstream and downstream flat box girders are smaller than those of single flat box girder.With decreasing of wind attacking angle,this suppression effect becomes weak and changes to amplification effect gradually.When the wind attacking angle is+2°,no vortex induced vibration occurs for single box girder,while comparatively large vortex induced vibrations is observed for twin box girders.