Long-Term Monitoring of Cable Tension Force in Cable-stayed Bridges using the Vibration Method. The Case Study of Binh Bridge, Vietnam

The tension force of a cable is an important parameter used to ensure the stable and safe working of cable-stayed bridges. This parameter needs to be strictly controlled throughout the operation of the bridge by installing direct force measurement sensors or indirect determination methods through analyzing vibration data of the oblique cables. This article introduces a method for predicting the cable tension value of a cable-stayed bridge using vibration-based data ready for application to in-service cable-stayed bridges. A method is proposed for calculating the effective length of stay cables while considering the influence of damping devices to improve the accuracy of cable tension assessment. The database to verify the model is a series of data on vibration testing in 32/80 cables of the Binh Bridge (Hai Phong) through inspections from 2007 to 2019. The bridge was damaged in 2010 and was completely repaired in 2012. The tension force monitoring during the damaged event, compared with that before and after the repair gives realizable results. The tension force was reduced over time and was recovered after the repair. Using vibration data to estimate the tension force is a fast and cost-effective method that helps minimizing risks during the exploitation and operation of cable-stayed bridges.