An Automated Algorithm for Identifying the fundamental frequency of Bridge Cable Vibrations

In practical bridge engineering, the cable tension can reflect the safety performance of the whole bridge structure. Vibration frequency based cable tension measurement method has been proven to be a practical effective approach. However, during the actual data collection process, environmental interference can easily affect the measurements, resulting in impure spectrum and making it difficult to identify the fundamental frequency (FF) used for cable force calculation. To address the problem, a fundamental frequency Automatic identification in Spectrum (FF-FAS) is proposed. First, in order to obtain the potential vibration FF from the spectrum, a feature peak screening algorithm is proposed to automatically identify the peak points in the spectrum, and assign weights according to the smoothness of the peaks and their equivalent width. Subsequently, to accurately identify the FF from the peaks, a new FF determination mechanism is designed, which automatically extracts the frequency sequence based on string vibration theory and selects the FF by synthesizing the contribution of each peak. {red}{The FF-FAS algorithm addresses the problem of traditional FF identification methods, which relys on peak detection and is easily affected by noise. The FF-FAS algorithm has been evaluated through both laboratory bridge model experiments and field tests on operational bridges, demonstrating significant improvement in identifying the FF compared to existing methods.