COUPLED MOTION BETWEEN STAY CABLES AND RIVULETS IN RAIN-WIND INDUCED VIBRATION

Rain-wind induced vibration of stay cable,whose mechanism is still unclear by now,severely affects the safety of cable-stayed bridges.The action between rivulet and cable surface is one of the difficulties in establishing theoretical models of rain-wind induced vibration.Here,assuming the action between rivulet and cable surface to be coulomb damping force and linear force,motion equations of cable and rivulet are simultaneously derived.Runge-Kutta method is used to solve the equation set,and the responses of cable and rivulet are obtained.Results show that the motion of cable has the characteristics of "velocity restricted" and "amplitude restricted",and it could be explained by the sudden dive of aerodynamic force.Whether the rivulet steadily exists on the upper surface of stay cable or not depends on the balance of aerodynamic force and gravity.Additional inertia force due to the motion of cable provides energy for the motion of the rivulet,and damping force between rivulet and cable surface dissipates energy to stabilize the rivulet motion.