Field observations of rain-wind-induced cable vibration in cable-stayed Dongting Lake Bridge

The cable-stayed Dongting Lake Bridge has been observed several times to exhibit large-amplitude cable oscillation under simultaneous action of rain and wind. To investigate excitation mechanism and response characteristic of the rain-wind-induced stay vibration, a series of field measurements lasting 45 days have been conducted on the Dongting Lake Bridge by deploying accelerometers, anemometers and rain gauge for continuous monitoring. This paper presents the measurement results of rain and wind excitations as well as dynamic response of a typical stay in three rain-wind excitation events. The measurement data show that under specific combination of rain and wind, the maximum acceleration response of the cable reaches 10 g and the maximum displacement response (peak-to-peak) is around 0.7 m. It is revealed that the large-amplitude rain-wind-induced stay oscillation occurs in the bridge when the mean wind velocity at deck level ranges from 6 to 14 m/s, the wind attack angle (relative yaw angle) ranges from 10° to 50°, and the rainfall is light to moderate (less than 8 mm/h). For the observed cable, the overall dominant mode of cable vibration during rain-wind excitations is the third mode. However, in the evolution process of this kind of vibration, the dominant mode may differ for different response segments.