Coaxial Cable Sensors for Distributed Crack Detection in RC Bridge Columns and Decks


A topology-based design concept of coaxial cable sensors, recently proposed and developed by the authors, is an enabling technology for crack detection in reinforced concrete (RC) structures. In this paper, after a brief review of the sensor working mechanism, the performances of two types of distributed crack sensors, respectively made of rubber and Teflon dielectric materials, were compared in turns of their sensitivity, spatial resolution, and ruggedness, and further validated with laboratory testing of a 4/5-scale, T-shaped, RC beam-column specimen. In 2003, two Teflon sensors were installed on one of the solid decks of a three-span continuous highway bridge, Dallas County, Missouri, to monitor their durability and the repeatability of their performance. Laboratory tests indicated that both types of sensors have high sensitivity, but the Teflon-sensor has a higher spatial resolution and a negligible spillover effect of the reflection coefficient waveform from the beginning to the ending part of the continuous cable sensor. At the 90° bend, however, the Teflon-sensor is more susceptible than the rubber-sensor to the rubbing action of the outer conductor of a coaxial cable against its dielectric layer. Load tests of the bridge indicated that cracks did not occur in the in-service structure under design loads. Both sensors were durable and gave reasonably consistent results.

Meeting Name

Tranportation Research Board Annual Meeting (2007: Jan. 21-26, Washington, DC)


Civil, Architectural and Environmental Engineering

Second Department

Electrical and Computer Engineering

Keywords and Phrases

Bridge decks; Coaxial cables; Concrete structures; Dielectric properties; Laboratory tests; Long span bridges; Reinforced concrete; Reinforced concrete bridges; Sensitivity; Sensors

Document Type

Article - Conference proceedings

Document Version


File Type





© 2007 Transportation Research Board, All rights reserved.

Publication Date

01 Jan 2007