Mitigation For Wind-Induced Vibration On Long-Span Cable-Stayed Bridges In Construction Stage

The reduction of stiffness of a bridge due to the increase of the main span might enable the bridge to have higher sensitivity to wind-induced vibration. And because of this, it is found that special mitigation treatment against wind loads have to be installed for some long-span bridges in order to provide greater safety margin and improve structural performance of the bridge during both construction stage and finished state. Also, research on mitigating wind-induced vibration of bridges in coastal regions or with significant national security, should necessarily be accomplished as emergency or supplementary plans. Different from the stiffness in the finished state, the stiffness of a bridge during the construction stage might not be fully formed, so significant structural response induced by wind loads might happen. Therefore, analyzing different methods to mitigate wind-induced vibration of long-span cable-stayed bridges, during construction stage, is likely to have important significance.This dissertation is mainly about wind-resistant behavior and related mitigation measures for a long-span cable-stayed bridge in China. With the aid of wind tunnel tests and theoretical analyses, the aerodynamic stability and safety performance of main girder, bridge towers, stay cables of this bridge in design or construction process are evaluated in this dissertation. Firstly, the wind tunnel tests on aeroelastic models of stayed towers with or without a tower crane in construction process are conducted and safety assessment is completed on the related experimental results basis. Secondly, the buffeting response of this bridge in maximum single and double cantilever stages, as well as the structural performance of the temporary tower-beam’s fixation, wind-resistant cables installed at the end of the main girder and the wind-resistant anchorage are investigated. Additionally, with respect to stay cables, mitigation measures to wind-induced vibration (the vortex vibration and the parametric vibration) are also presented in this dissertation.