Structural identification of cable-stayed bridge under back-to-back typhoons by wireless vibration monitoring

• Structural identification of a cable-stayed bridge under typhoons is performed.
• Structural stiffness change due to wind speed change is quantitatively estimated.
• STFT analysis should be applied for the bridge aerodynamic during typhoons.

In this paper, structural identification of a cable-stayed bridge under back-to-back typhoons is performed using vibration responses measured by a wireless sensor system. Firstly, a cable-stayed bridge with the wireless monitoring system is described. Wireless vibration sensor nodes are utilized to measure accelerations from the deck, pylon and stay cables of the bridge. Secondly, dynamic responses of the cable-stayed bridge under the attack of two consecutive typhoons, Bolaven and Tembin, are analyzed under various wind speeds. Stochastic subspace identification method and short-time Fourier transform analysis are selected to examine wind-induced variations of the bridge’s responses based on the field measurements under the two typhoons. Finally, the structural identification of the bridge is performed under various wind velocities to examine the typhoon-induced variations of the bridge’s structural properties. The variations of dynamic characteristics due to the typhoons are turned into the changes of the bridge’s stiffness (or flexibility) via the fine-tuning process.