Crack detection of a 15 meter long reinforced concrete girder with a single distributed cable sensor

A new concept of designing cable sensors for health monitoring of large-scale civil infrastructures has recently been proposed by the authors. The concept was developed based on the change in topology of the outer conductor of a coaxial cable sensor. One such sensor was fabricated with its outer conductor tightly wrapped with tin plated steels that are covered by soldering. It was mounted near the surface of a 15 m long reinforced concrete girder with a 762 mm square hollow cross section and 152 mm thick walls. The girder was tested under a progressively increasing cyclic torsion creating 45° inclined cracks around and along the girder. The main objectives of this study are to implement the distributed cable sensor technology in large-scale reinforced concrete structures, to understand the performance of a sensor under cyclic loading for detecting and locating cracks, and, finally, to address a number of implementation issues including signal loss, non-uniformity, recoverability and measurement uncertainty.