Vibration analysis of Tianxingzhou long span suspension bridge scheme

In this paper, a three-dimensional dynamic finite element model is established for the Tianxingzhou long span suspension bridge scheme in Wuhan, China. The two reinforced concrete bridge towers are modeled by three-dimensional beam elements. The cables and suspenders are modeled by cable elements taking account of their geometric non-linearity. The members of the stiffening truss are also represented by three-dimensional beam elements. The steel deck is modeled by shell elements. The model analysis is then performed to determine the natural frequencies and mode shapes of lateral, vertical, torsional, longitudinal, and coupled vibrations of the bridge. The results show that the natural frequencies of the bridge are very closely spaced, with the first 40 natural frequencies ranging from 0.1259 to 1.0802 Hz only. The computed normal modes indicate the interactions between the girder, cables, and towers. Significant couplings are also observed between torsional and lateral modes. The established dynamic model and the computed dynamic characteristics can serve further studies on the aerodynamic analysis and a long-term monitoring of the bridge.