CONTROL OF WIND-INDUCED BUFFETING RESPONSES OF A MULTI-TOWER CABLE-STAYED BRIDGE USING VISCOUS DAMPERS

This paper presents an investigation for the mitigation of wind-induced buffeting responses of Jiashao Bridge, a six-tower cable-stayed bridge. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS using a transient dynamics-analysis function. The effectiveness of viscous fluid dampers on the mitigation of buffeting responses of the multi-tower cable-stayed bridge is further investigated. The analysis results reveal that: 1) For wind-induced vibration control of bridge deck and tower of the multi-tower cable-stayed bridge, the reduction ratio increases with the increase of damping coefficient c up to a certain level, giving maximum values for its reduction ratio. Moreover, the smaller the damping exponent α, the smaller damping coefficient c corresponding to the maximum reduction ratio; 2) The installation of a rigid hinge in the middle span of the bridge deck will significantly increase the lateral buffeting response of the bridge deck. The maximum reduction ratio for the lateral buffeting displacement in the middle span of the bridge deck is about 50% using viscous dampers; 3) In Jiashao Bridge, the secondary side towers restricted with the bridge deck result in a concentration effect of base shears and moments. Thus, the base forces of secondary side towers are significantly larger than those of other bridge towers. The maximum reduction ratio for the base forces of secondary side towers is about 55%, using viscous dampers; 4) The installations of viscous fluid dampers are beneficial for the uniform distributions in the wind-induced responses for each tower and each span of the multi-tower cable-stayed bridge. Therefore, the vibration reduction effect is relatively small for those towers and spans with relatively small wind-induced responses.