分离双钢箱梁涡激振动气动干扰试验研究

Experimental study on aerodynamic interference effects on the vortex-induced vibration of twin separate steel box girders

间距和风攻角是分离双钢箱梁涡激振动干扰的主要影响因素。通过节段模型风洞试验研究了-5°^+5°之间8个不同风攻角下分离双钢箱梁在极小间距(D/B=0.025,D为双箱梁的净间距,B为单箱梁宽)、较小间距(D/B=0.1)、中等间距(D/B=0.4)和较大间距(D/B=3.0)时的涡振特性,并将结果与单钢箱梁的结果进行了对比。研究发现:在极小间距和中等间距时,气动干扰放大了上下游箱梁的涡激振动;在较小间距时,双箱梁的涡振特性与来流风攻角密切相关,随着风攻角的逐渐变小,气动干扰对上下游箱梁涡激振动的影响由抑制效应逐渐转变为放大效应;在较大间距时,上游箱梁对下游箱梁涡激振动存在一定的抑制效应,下游箱梁对上游箱梁涡激振动的影响可以忽略。

The vortex-induced vibration characteristics of twin separate steel box girders in 4 different spacings under 8 different wind attacking angles ranging from -5° to ＋ 5° were investigated and the results were compared with those of a single steel box girder through sectional model wind tunnel tests. The 4 spacings are D/B = 0. 025（ very small spacing）,D/B = 0. 1（ comparatively small spacing）,D/B = 0. 4（ medium spacing） and D/B = 3. 0（ comparatively large spacing）,where D is the net spacing between the twin box girders and B is the width of the single box girder. The test results show that in the very small spacing and medium spacing,the vortex-induced vibrations of both the windward box girder and leeward box girder are amplified. In the comparatively small spacing, the vortex-induced vibration characteristics of both the windward box girder and leeward box girder are closely related to the wind attacking angle. With the decreasing of the wind attacking angle,the aerodynamic interference effect changes from suppression effect to amplification effect gradually. In the comparatively large spacing,the aerodynamic interference effect on the vortexinduced vibration of windward box girder can be neglected. The vortex-induced vibration of leeward box girder is suppressed due to the existence of windward box girder.