Enhancing Fatigue Life of Steel Plates with CFRP Laminate: Effects of Curing Temperature, Stress Range, and Adhesive Thickness

Steel bridges often require rehabilitation and retrofitting to address cracks and deteriorations caused by age, environmental factors, and increased loads. Carbon fibre reinforced polymers (CFRP) strengthening is a reliable and efficient method used for strengthening steel structures, particularly in steel joints subjected to cyclic loading from traffic. This study explores the impact of adhesive curing temperature on the fatigue behaviour of CFRP-steel joints under various stress ratios and ranges, it also evaluates the effect of adhesive thickness on fatigue life of the joint. Results indicate that curing temperature has no effect on fatigue behaviour, and the stress range-fatigue limit is constant at 30 MPa. Strain readings were taken to monitor debonding initiation, and the failure mode was predominantly steel-adhesive debonding. Adhesive thickness <2 mm has no significant effect on fatigue life of steel joints strengthened with CFRP. This research provides valuable insights for improving durability of steel bridges and structures.