Effect of hygrothermal and freeze-thaw cycles on mechanical properties of kiloton CFRP cable with self-monitoring function

Hygrothermal and freeze-thaw cycles are the key factors that lead to the performance degradation of carbon fiber reinforced polymer (CFRP) composite in bridge structures. A comprehensive investigation into the performance evolution of CFRP rods and large-scale CFRP cables under such cyclic conditions is imperative. In the present paper, the evolution of mechanical properties and glass transition temperature (Tg) of CFRP rod under 50 hygrothermal and freeze-thaw cycles was investigated. The verification data on the mechanical performance of full-scale kiloton CFRP cables post-exposure to these cycles was obtained. The optical frequency domain reflectometry (OFDR) strain monitoring was used to obtain the effect of hygrothermal and freeze-thaw damage on mechanical properties. The results showed that the mechanical performances of the CFRP rod had no significant degradation after hygrothermal and freeze-thaw cycles, while Tg of the CFRP rod decreased by 6.72 %. In addition, the maximum thermal strain and moisture strain of CFRP cable were 264 mu 8 and 38 mu 8, respectively, indicating a negligible influence of hygrothermal and freeze-thaw damage on their mechanical properties. Furthermore, CFRP cables demonstrated the capability to withstand 50 cyclic loads (0.40-0.80 ultimate tensile loading) post-exposure, with a final residual tensile strength retention of 105 %. These findings provide key verification data for the durability design of CFRP cables in bridge structures.