Smart carbon fiber reinforced polymer (CFRP) strand: Mechanical properties, self-sensing characteristics, and engineering applications

Conventional monitoring methods for steel cables often face limitations, such as insufficient measurement accuracy and suboptimal long-term reliability. Additionally, the inherent corrosion susceptibility of steel cables poses significant compatibility challenges with standard installation procedures for Fiber Bragg Grating (FBG) sensors. To address these issues, this study leverages the superior corrosion resistance and enhanced sensor compatibility of carbon fiber reinforced polymer (CFRP) composites. Specifically, smart CFRP strands were developed by embedding FBG sensors within the core of CFRP rods, followed by an extensive investigation of their fundamental mechanical properties. Smart composite cables were then fabricated by integrating these CFRP strands with conventional steel strands, imparting self-sensing capabilities to the hybrid system. This innovative configuration not only enhances the measurement accuracy of cable force monitoring but also significantly improves the long-term durability of embedded FBG sensors, thus achieving effective coupling between structural load-bearing and sensing functions. Quasi-static tensile tests conducted at 10 %–40 % of the maximum cable force (FC max ) revealed a linear correlation coefficient of 0.99 between FBG wavelength shifts and axial strains, with total monitoring errors confined to below 11.5 % (hysteresis error ξ H ≤ 10 %, linearity error ξ L ≤ 3 %, repeatability error ξ R ≤ 6.6 %). Notably, under ultimate loading conditions, the monitoring accuracy remained at 99.2 %, with sensors maintaining functionality until CFRP strand fracture, thereby validating the system's reliability for cable force monitoring in bridge engineering. Field validations conducted on the Liuheng Highway Bridge (Ningbo-Zhoushan Port) and the Anluo Yellow River Bridge demonstrated excellent monitoring performance, highlighting the system's promising potential for infrastructure health monitoring applications. • Integration of smart CFRP strands. • Smart CFRP strands mechanical and sensor performance testing. • Preparation and performance testing of smart CFRP-steel strand composite cables. • Engineering applications of smart CFRP-steel strand composite cables.