Practical Solutions for Reducing Rain-Wind-Induced Vibrations of Cables, in Cables-Stayed Bridges.

Abstract

Rain vibration of cables is becoming a matter of great concern recently in Japan and other country for design and construction of cables-stayed- bridges. The features of rain vibration are the strong influence of rain on wind-induced oscillation of cable. The cables in cable-stayed bridges, which are stable with respect to wind acting in dry condition, became very unstable with rain, and large amplitude oscillation of cable could be developed under low speed wind. The principal parameters that give a great influence in this phenomenon can be classified in two groups. First the group of the situation of cable were included: the orientation of cable, wind speed, reins intensity. In second group named cables properties were are included natural periods, damping ratio and property of the surface of cables.In this article is presented only a part of the bibliographic study performed at the Laboratoire Central des Ponts at Chausse, Paris. This part is focused on two aspects, the mechanism of the problem and the solved solution by surface modification of cables for elimination of this kind of vibrations on the cables. We point here the fact that even many investigation are made this phenomenon is not well known and not jet is found a mathematical model to simulate exactly the real phenomenon.Here are given only those solutions that tend two stabilise the cable by modification of the surface of the cable. These modifications of the surface of cables tend to "destroy" the water rivulets created on the surface of the cables. Doing so, for every speed and direction of wind and for any rain intensity the water rivulet have not chance to be created on the surface of the cable. These findings are taken from the experiments and investigation on the cables-stayed bridge of Normandy, Paris and cables-stayed bridge of HIGASHI-KOBE, Japan.