Instantaneous identification of tension in bridge cables using synchrosqueezing wave-packet transform of acceleration responses

Abstract

Real-time monitoring of cable tension is essential in detecting damage and assessing the service performance of bridges. Vibration frequency-based methods for cable tension identification have been increasingly investigated in bridge engineering over the last decade. However, cable tension estimation using vibration frequency-based methods can only obtain the average cable tension over a specified time interval. Therefore, identification of instantaneous variation of cable tension still remains to be a pending issue. To tackle this problem, this study proposes an algorithm defined as Synchrosqueezing Wave-packet-based Instantaneous Frequency Tracking (SWIFT) to identify the instantaneous change of cable tension by monitoring its acceleration responses. The proposed algorithm can extract the time-varying instantaneous frequency of the tested cable and further identify the variation of instantaneous cable tension by time-frequency analysis of the transversal motion. Moreover, the identification accuracy and noise robustness are numerically verified using a synthetic time-varying multi-frequencies signal. Finally, experimental validation is conducted on a prototype cable and an actual cable of the Sutong Yangtze River bridge, respectively. The theoretical, numerical, and experimental results show that the proposed method can precisely identify instantaneous cable tension under noisy conditions.