The Study Of Cable Structrue Aeroelasticity And Its Wind-Induced Vibration

Cable structure play an important role in many civil engineering structures, such as transmission lines, guyed towers, cables-stayed bridges, suspension bridges and some space structures. Due to their lighter weight, greater flexibility and lower inherent damping, however, cables in a structure are prone to vibrations under different types of dynamic loadings. This dynamic problem can affect human comfort and even the structural safety. Aerodynamic load will become control load instead of weight of structure when they are in natural conditions. Cable structure was always induced large amplitude vibration by rain and wind, although with common wind speed. Theory system of rain-wind induced vibration of cable is still faultiness, there are many problems should be studied deeply.Two aspects problem were studied in this project, One-degree model of galloping of cable structure and two-degree model of rain-wind-induced vibrations of cable structure.One-degree model of galloping of cable structure was studied by CFD software Fluent. First, the model of cable structure with half cylinder form was built by Gambit in incompressible flow, and then plot grid in detail according to the flow field characteristics around the cable structure. The parameters such as boundary pressure, fluid attribute etc. were set in CFD software Fluent. The flow field characteristics around the cable structure and the drag coefficient and lift coefficient according to different attack angel were achieved by Fluent also. The expression of drag coefficient and lift coefficient about attack angel were attained by polynomial fitting method. In aspect of numerical computation, One-degree differential equation about galloping of cable structure was built. The original system was studied by numerical computation with symbol algebra language Mathematica. The phase diagrams of cable vibration were achieved, which showed that their movement converged to limit circles. In aspect of analytical computation, the system was studied by averaging method. Approximate solution of one order of system was achieved, the result fits with experiment well. The influences of damping of cable, wind speed were discussed by numerical computation method.Two-degree model of rain-wind-induced vibrations of cable structure with moving upper rivulet was studied. Considering the effects such as rivulet shaking, angle of yaw, the non-linear dynamics differential equation of this system was built. It was studied by numerical computation with symbol algebra language Mathematica. The phase diagrams and time History of cable structure and rivulet were achieved. It showed that their movements were stable ones. The influence of density of air, damping of cable, angle of yaw etc. were discussed at the same time.