Fatigue Behavior of Cracked Steel Plates Strengthened with Different CFRP Systems and Configurations

Using carbon-fiber-reinforced polymer (CFRP) materials can extend the fatigue life of damaged steel structures. However, several issues still need to be studied. In this paper, experimental and numerical studies were conducted on the fatigue behavior of cracked steel plates strengthened with CFRP materials. A total of 10 specimens were designed, including six central-cracked and four edge-cracked specimens. The repair effectiveness of the different CFRP systems and CFRP configurations were compared under the equivalent CFRP tensile stiffness. The test results indicate that the CFRP can effectively decrease the crack growth rate and prolong the fatigue life of cracked steel plates. For the central-cracked specimens, the fatigue life can be extended by 3.5–4.9 times that of the unstrengthened specimens. For the edge-cracked specimens, the extension ratio of the fatigue life was 6.9–11.3. Under the equivalent CFRP tensile stiffness, the repair effect of the CFRP plates was better than that of the CFRP sheets, and the different CFRP configurations had an effect on the fatigue repair effectiveness of the specimens. A finite element (FE) model was developed to evaluate the stress intensity factor of the specimens. Based on the FE results and the linear elastic fracture mechanics theory, the fatigue life and the crack propagation curve were predicted. The numerical and experimental results were in good agreement.