Cable Tension Estimation Using Vision-Based Monitoring System Under Weather Conditions

Abstract

AbstractRecently, with the continuous development of materials, designs, and construction technologies, the construction of long-span bridges has been increasing. Especially, for long-span bridges using cables, it is important to monitor the safety of the bridges continuously by measuring the tension of the cables under construction and in traffic use. Among the various methods for evaluating the tension of cables, the vibration method, which estimates the tension using shape conditions and natural frequencies measured from the cables, is widely used at the moment as it is more economical and convenient than the direct method, which measures the stress of cables using a load cell. Accelerometers, as one of the conventional sensors being used to monitor tension of existing cable-supported bridges, may not easy to install at cables and require the considerable cabling work to facilitate a direct connection between each sensor and DAQ logger. For this reason, a technique using digital image processing, which is one of non-contact sensing systems, may be needed to monitor the tension of the cable. Therefore, in this study, for the monitoring of cables, a vision-based monitoring system using the image processing technique was developed, which can estimate the dynamic characteristics of many cables using a single system. The developed system was applied to a cable-stayed bridge in traffic use, and to verify the possibility of the long-term monitoring of cables, the recognition rate of cables was investigated using images acquired under various weather conditions.KeywordsCable-supported bridgeTensionVision-based monitoring systemImage processing techniqueCable recognition rate