Fatigue performance criteria for CFRP Reinforcements Based on RC behavior in civil construction

This study aims to develop fatigue performance criteria for Carbon Fiber Reinforced Polymer (CFRP) reinforcements, considering the mechanical behavior of Reinforced Concrete (RC) structures. Fatigue tests were conducted to create S-N and ε-N curves based on different fiber-volume fractions (40 %, 50 %, 60 %), and these curves were used to evaluate and apply the fatigue performance of CFRP reinforcements. The results quantitatively confirmed that specimens with a 60 % fiber-volume fraction exhibited reduced fatigue resistance due toinsufficient fiber-matrix bonding. Additionally, SEM analysis revealed the mechanisms behind early delamination and micro-cracks caused by long-term cyclic loading. This study developed practical fatigue performance evaluation criteria based on S-N and ε-N curves, providing useful guidelines for evaluating the durability and designing CFRP reinforcements under various load conditions. The flexural-tensile fatigue method proposed in the study is expected to overcome the limitations of traditional tension-tension fatigue tests and contribute to improving the durability and performance of CFRP reinforcements.