Time-varying damping ratio identification for structures subjected to traffic loads using signal stabilization technique

Abstract

The non-stationary traffic loads induce non-stationary structural responses, posing a significant challenge for the accurate identification of damping ratios. At the same time, the dynamic parameters of the vehicle-bridge system vary due to the vehicle-bridge interaction (VBI) effect. To address the issue of non-stationary structural responses in both amplitude and frequency under traffic loading, this paper proposes a signal stabilization technique to identify the time-varying damping ratio. The signal is stabilized over a short window, after which the structural parameter information is extracted by estimating the autocorrelation function. Two error suppression techniques are proposed. In combination with the time-varying autoregressive model, the damping ratio is recursively identified using Kalman filtering. The accuracy of the method was verified through numerical simulations, and the time-varying parameters of the VBI system were identified in laboratory experiments. Finally, the time-varying damping ratios of a real bridge were identified to verify the effectiveness of the method. The results demonstrate that the proposed method can identify the variation of the bridge damping ratio due to traffic loads, both in laboratory tests and analyses of real bridges. The proposed method provides a foundation for an in-depth study of damping ratios.