Full-length strain and damage monitoring for carbon fiber reinforced polymer cable based on optical frequency domain reflectometry

Lightweight, high-strength, corrosion-resistant, and fatigue-resistant carbon fiber reinforced polymer composite (CFRP) cables for cable-stayed or suspension bridges have been considered an excellent alternative to traditional steel cables. In the present paper, optical frequency domain reflectometry (OFDR) technology was applied to realize self-monitoring of the full-length strain and damage of CFRP rod-cable. The full-length axial tensile strain distribution of a 35 m CFRP cable was verified with the tensile test. The strain accuracy was verified to be 1.61 %, with a spatial resolution of ≤ 10 mm and a strain precision of 3.92 με throughout the full-length strain distribution. In comparison to the actual cable force, the cable force distribution, which is based on partial self-monitoring CFRP rods, demonstrates a deviation of approximately 1.6 %. The rod fracture damages in the CFRP cable were identified using wavelet smoothing, resulting in a localization error of ≤ 0.645 m and a quantification error of less than 15 %. According to the present study, methods to determine the cable force distribution and fracture damage for a CFRP cable were proposed.