Stay cable tension estimation using a vision-based monitoring system under various weather conditions

Recently, the construction of long-span bridges has increased due to continuous developments in materials and construction technologies. For long-span bridges that use cables, it is important to continuously monitor bridge safety by measuring cable tensions under construction and in traffic use. Among the many methods of measuring cable tensions, the vibration method, which estimates tensions based on cable shapes and natural frequencies, is currently popular because it is more cost-efficient and convenient than direct methods. Studies on the estimation of cable tensions using image measurement systems are actively underway, but they are used for routine inspections rather than in fixed systems for long-term monitoring of cable tensions. In this study, a vision-based monitoring system to measure cable tensions is installed. The system is applied to a cable-stayed bridge in traffic use. To verify the possibility of long-term monitoring cable tensions, images acquired under various weather conditions were used to estimate the cable tensions.