Real-time online intelligent perception of time-varying cable force based on vibration monitoring

Abstract

During the service period of cables, the corrosion fatigue is the principal damage form under the combined action of traffic loading and external environment. The real-time and accurate perception of the time-varying cable force in service is the foundation for exactly evaluating the safety status of cable. However, most of the existing methods identifying cable force can only obtain the average cable force over a period of time, besides, although a few methods can detect the time-varying cable force, they cannot meet the requirements of time-frequency resolution. This paper proposes a real-time intelligent vibration-based perception method of the time-varying cable force based on the block recursive APES method and cable dynamic stiffness analysis theory. Through the efficient recursive APES method, the real-time intelligent perception of time-varying frequencies is abstracted from the real-time monitoring vibration signal of the cable. Based on the accurate dynamic analysis model of the cable, the cable forces and modal frequencies calculated by the theoretical formula are fitted to obtain an accurate identification method for the time-varying cable force, which can meet the real-time and accuracy requirements at the same time. Combining the above two methods, a real-time intelligent perception method for perceiving the time-varying cable force is proposed. In order to verify the feasibility and accuracy of the proposed method, cases on real bridge cables were analyzed, and the selection methods of order, range and accuracy of time-varying frequency and cable force were proposed. The results demonstrated that the proposed method can realize the real-time accurate perception of time-varying cable force, and the temperature effect has an obvious influence on the time-varying cable force. In the statistical analysis of cable stress amplitude, the influence of temperature trend should be removed.