Torsional vibration control of suspension bridge decks using tuned liquid column damper

This dissertation mainly focuses on the theoretical and experimental investigation on torsional vibration control of suspension bridge decks by using tuned liquid column damper. This research leads to a pioneer study in this area which has not been dealt with by researchers up-to-date. A considerable contribution is made to the vibration control theory and method in the suppression of the torsional oscillation of bridge decks using passive tuned liquid column dampers.; A nonlinear mathematical model of the damper is first developed. The system governing equations are derived in consideration of bridge deck and damper interaction. Dynamic analysis for the TLCD-bridge deck system under harmonic loading is performed in both time domain and frequency domain. In order to verify the theoretical model and to investigate the control performance under different TLCD parameters, a detailed experimental study is carried out. A large scale experimental model simulating TLCD-bridge deck interaction is designed and a series of free and forced vibration experiments are conducted under different TLCD configurations and parameters. A close agreement is obtained between experimental and theoretical results. Extensive parametric and numerical studies are also performed to seek optimal control parameters of a TLCD in suppressing torsional vibration of bridge decks. The optimum TLCD parameters are determined for both damped and undamped bridge decks using two different optimization approaches. The influence of TLCD parameters on the control performance is extensively investigated. A comprehensive study is made on the wind-induced vibration control of suspension bridge decks by using the tuned liquid column damper. The related vibration control principle and method under random wind loading are developed. Two important aspects: buffeting response and flutter stability of the bridge, are considered. A stochastic equivalent linearization is made to the nonlinear system. The random vibration analysis is performed for the buffeting control of bridge decks, and the critical flutter condition for the bridge deck is identified. Finally, a case study of the Tsing Ma long suspension bridge in Hong Kong is carried out. Both the reduction of buffeting response and the increase of critical flutter wind velocity are discussed. It is concluded that TLCD can be a very effective device to suppress torsional vibration of long suspension bridge decks, either for reducing the buffeting responses or improving the flutter stabilities.