Distributed cable sensors for structural damage detection: Implementation issues

A new concept for the design of coaxial cables was recently proposed and developed by the research team by introducing the change in topology of the cable structure when the cable is subjected to strain effects. In this study, three implementation issues are discussed to further advance the emerging technology towards its commercialization and implementation for crack monitoring and detection of reinforced concrete (RC) structures. They include plasma sprayed coating of a coaxial cable sensor, correlation between the reflection coefficient and the width of a crack, and interference of steel reinforcing bars with the electromagnetic field used for time-domain reflectometry measurements. Test results have shown that the sprayed coating can significantly enhance the uniformity of coaxial cable sensors and thus the quality of measured data. With controlled cracking tests, the peak reflection coefficient was found linearly related to the width of a crack. Furthermore, the interference by the adjacent steel bars is negligible even when a coaxial sensor is nearly in contact with a reinforcing bar.