Vibration mitigation of long stay-cable using MR dampers under semi-active control strategy

Long-span cables are susceptible to vibration with large amplitude under wind/rain loading or support excitation.To overcome these problems,a theoretic model for the cable-damper system is formulated by accounting for the cable inclination and sag effect based on the Hamilton principle.The discrete Magnetorheological(MR) dampers were installed on the 330m-long cable.The dynamic response performances of a cable with MR dampers are explored using Spencer photometric model.The semi-active control strategies of cable vibration are provided two ways.One is based on the direction of both displacement and velocity,and the other is based on combined the optimal damper force and the voltage control together.The optimal damper force are derived by LOC(linear optimal control),PA(pole assignment),QOC(quasi-optimum control) and VSS(variable structure system).The voltage is converted by COC(clipped-optmal control),Hrovat method and Lyapunov direct method.The primary measure of damper performance considered is the root mean square(RMS) cable deflection integrated along the length of the cable and the whole time.The comparison study among the semiactive under the strategy and the optimal passive MR damper indicated the advantages of semi-active dynamic adjust control with a better control performance when MR dampers marker is within the effective region.