Study On Parameter Vibration, Rain-Wind-Induced Vibration And Resistance Measures

The stay cable is one of the principal force members of cable-stayed bridges. Under the impetus of external factors it would be vulnerable to a variety of harmful vibration, owing to its properties of high flexibility, little weight and damp. This thesis focuses on parameter vibration with great amplitude due to the structural characteristics of bridges without rain and rain-wind-induced vibration of stay cable at a certain position.The mechanisms of parameter vibration are briefly analyzed and the Zhanjiang Gief Bridge is investigated by separately establishing the finite element model of the whole bridge and of individual cable with consideration of drooping. It follows from the investigation that a little impetus can lead the great transverse vibration of cable, when the frequency of impetus acting on the bridge surface is twice that of self-vibration of cable (generally the value of first order). It is a well-accepted measure restricting parameter vibration by increasing the damp of cable or bridge surface. After exerting a certain amount of damp to easily vibratile cable of the Zhanjiang Haiwan Bridge the greatest amplitude of cable is markedly reduced and finally controlled within a certain range.The rain-wind-induced vibration of stay cable is a new phenomenon of wind-induced vibration, which was originally discovered in 1980's. Currently, the generation mechanisms of rain-induced vibration have yet to be reached. This thesis deeply analyzes a few existing generation mechanisms and illuminates the basis, advantages and disadvantages of some possible mechanisms. In the mean time, the influence of wind speed, wind direction, precipitation and damp of cable on rain-induced vibration of stay cable is systematically investigated by means of wind tunnel tests of section models of two kinds of stay cable with different diameters. This thesis also places much importance on exploring the effects of the two aerodynamic measures (setting helix ribs or dimples on cables), restricting the rain-wind-induced vibration and comparing the resistance coefficient of the two aerodynamic measures by static test. Based on it, proposals about their application are made.In addition, some structures and aerodynamic measures restricting wind-induced vibration of various stay cable are proposed.