Fatigue performance of carbon fiber-reinforced polymer strengthened single-edge cracked steel plates: Effects of adhesive property and CFRP arrangement

Carbon fiber-reinforced polymer (CFRP) is increasingly used to improve the fatigue behavior of damaged steel structures due to its advantages, including high strength and convenient processing. However, several issues, such as the effects of the adhesive property and CFRP arrangement, still need to be studied. In this study, a total of 20 single-cracked steel specimens were tested under fatigue load, including two unstrengthened specimens, six single-sided strengthened specimens, and 12 double-sided strengthened specimens. The failure mode, fatigue life, crack propagation pattern, and interface damage development were obtained from experiments. The results show that epoxy resin structural adhesives (adhesives Araldite 420 and J133C) have the best bonding properties with CFRP. For the conventional epoxy adhesives, Araldite 420 and J133C can considerably improve fatigue life, which increased by more than 44.84 times to unstrengthened specimens. CFRP plate strengthening can significantly improve the fatigue life of single-edge cracked steel plates. For the double-sided strengthened specimens, the fatigue life can be improved by 6.93-44.84 times that of unstrengthened specimens. For the single-sided, the fatigue life can be improved by 2.24-2.77 times. Properties of epoxy adhesive have a more significant effect on fatigue life compared to the thickness of the CFRP plate due to debonding.