Abstract
Stay cables are important structural members of cable-stayed bridges, which play a significant role in the health monitoring and assessment of cable-stayed bridges. The in-service cable force, which varies from the effects of vehicle load, wind load and other environmental factors, may cause fatigue damage in stay cables. Traditional force identification methods can only calculate the time-average cable force instead of the instantaneous force. A novel method has been proposed in this paper for identifying time-varying cable tension based on the variational mode decomposition (VMD) method. This recent method decomposes signals and adaptively estimates instantaneous frequency combined with the Hilbert–Huang transform method. In the proposed study, the time-varying modal frequencies were identified from stay cable acceleration data, and then the time-varying cable tension was identified by the relationship between cable tension and identified fundamental frequency. Scaled and full-scale models of stay cables were implemented successively to illustrate the validity of the proposed method. The results showed that the variational mode decomposition (VMD) method has a good effect on identifying the time-varying cable forces, even the sudden changes in cable force. According to the cable force identification results, the maximum error was 8.4%, which meets the actual application of time-varying cable force measurements. An on-site test was also implemented to monitor the cable force during a construction period, and the results showed that the proposed method can provide accurate real-time results for evaluation and decision-making.
Highlights
Stay cables are the main load-bearing and force-transmitting members of cable-stayed bridges
Aiming at time-varying cable force identification, this present study leverages the advantages of variational mode decomposition (VMD) and the Hilbert–Huang transformation (HHT) theories to propose a satisfactory method, and a single accelerometer without extra information such as wind speed was used for more convenient application
A new mothod based on VMD was established to identify the timevarying force of stay cables
Summary
Stay cables are the main load-bearing and force-transmitting members of cable-stayed bridges. Stay cables usually have stiffness, so they can be considered as supported beams According to this theory, the cable force can be calculated according to the following formula:. Related studies [13,14] proposed several practical simplified formulas according to this theory and the measured natural frequency of the stay cable. Yang et al [20] proposed an algorithm called complexity pursuit to identify timevarying cable tension forces according to acceleration data This method requires two independent acceleration data points from two accelerometers on a cable. Aiming at time-varying cable force identification, this present study leverages the advantages of variational mode decomposition (VMD) and the Hilbert–Huang transformation (HHT) theories to propose a satisfactory method, and a single accelerometer without extra information such as wind speed was used for more convenient application.
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