Suppression of Vibrations Induced by Fluctuating Wind for Long-Span Cable-Stayed Bridge Using MR Dampers

Abstract

Cable-stayed bridges subjected to wind excitations will cause intense vibration due to their high flexibility in characteristic. Employment of magnetorheological (MR) dampers to realize the vibration smart-control of cablestayed bridges has become a considerable research topic in recent decades. In this paper, the plane truss finite element model (FEM) of a cable-stayed bridge with MR dampers is established. Fluctuating wind field is generated using the weighted amplitude wave superposition (WAWS) method and Kaimal spectrum, and then the time-history sample curve of wind speed is obtained. Fluctuating wind-induced vibration of the long-span cable-stayed bridge installed with MR dampers is analyzed by linear quadratic regulator (LQR) classical optimal control strategy and LQR tri-state control strategy. After the optimal control force is calculated by LQR classical optimal control strategy, control parameters and the input currents of MR dampers can be determined according to the windinduced vibration by LQR tri-state control. Results show that longitudinal and vertical wind-induced vibration responses of the box girder of the cable-stayed bridge are reduced obviously when MR dampers are arranged between the box girder and pylons.