It was found in recent years that dry cable galloping is a new vibration type of stay cables. It became an important factor considered in bridge design because of large amplitude and serious demage. Three different surface roughness cable models were investigated with high frequency balance technique and displacement meter in a wind tunnel. Based on analyzing drag forces, lift forces and vibration amplitudes under different Reynolds number, it was found that asymmetric and unstable flow field appears under critical Reynolds number; cable balance positions are changed and large amplitude vibrations are induced due to unstable lift forces in the flow field; critical Reynolds number decreases with increase in surface roughness; for prototype cables with smooth surface, as wind velocity corresponding to critical Reynolds number is rather high, the possibility of large amplitude vibration is small; however, cables surface becomes rough under environments, such as, sunshine, wind, rainfall, and floating dust adherence, thus large amplitude vibration becomes possible under common high wind velocity; this is one of the possible mechanisms of dry cable galloping for prototype cables.%干索驰振是近年来发现的斜拉索振动类型,由于振幅大、破坏严重,是设计中需要重点考虑的问题之一.通过三种不同粗糙程度的斜拉索模型测力风洞试验,得到了模型气动阻力和气动升力随雷诺数变化的曲线;通过测振风洞试验,得到了模型振动振幅随雷诺数变化的曲线.分析表明:在临界雷诺数区域,模型周围的流场不对称且不稳定,模型产生平均气动升力,不稳定的升力导致模型平衡位置的变动,同时引起模型发生大幅振动.随着斜拉索表面粗糙度的增大,临界雷诺数变小.对于表面光滑的斜拉索,由于临界雷诺数对应的风速很大,所以实桥发生这种振动的可能性较小.但是斜拉索在诸如风吹日晒、漂浮物黏着等环境下逐渐变得粗糙,导致临界雷诺数减小,使得在相对小的风速下斜拉索发生临界雷诺数区域的大幅振动成为可能.这是实桥斜拉索发生干索驰振的可能机理之一.
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