Experimental Investigation Of Aerodynamic Measures On The Influence Of The Aerodynamic Forces Of Cables In Cable-Stayed Bridges

A lot of serious damage for the bridge structure is caused by the rain-wind induced vibration of cables in cable-stayed bridge. Kinds of measurements have been taken in projects to solve this problem, among which the aerodynamic measurement,wrapping helical wires on the surface of stay cable, is one of the most commonly used.The wind load on cables in cable-stayed bridge occupied large proportion in the whole bridge wind load on the large span cable-stayed bridge. The existence of the helical wires on the surface of the stay cables will change the aerodynamic shape,which will make the aerodynamic force on the cable changed. Therefor it is necessary to study the effects of aerodynamic measures for the aerodynamic force. And it turns out to be an urgent issue to decrease the wind load on the cables in cable-stayed bridge under the premise of vibration suppression.In this paper, wind tunnel tests for aerodynamic forces on one smooth stay-cable and twenty five helical wire stay-cables have been performed with two balances measuring at the same time. The Reynolds number ranges from 130~430 thousand.The diameter of the cable is 120 mm and the length of it is 1.7 m. The aerodynamic coefficient and the frequency of vortex shedding of smooth stay-cable and helical wire stay-cable are analyzed on the basis of load data. Finally, the optimization helix parameters were studied combined with the existing vibration test results. Reynolds Number Effect of stay-cable can be decreased effectively by wrapping helical wires on the surface of stay cable. When the Reynolds number exceds 420 thousand, the drag coefficient of stay-cable decrease with the increase of pitch of the helix or the decrease of the diameter. The vortex shedding energy of stay-cable can be decreased effectively by wrapping helical wires on the surface of stay cable. The optimization method helix parameter is proposed and the data needed for the optimization of helix parameters, which provides the information and reference for the future researches and applications.