Fatigue behaviour of CFRP strengthened steel plates with different degrees of damage

• We tested 6 specimens strengthened by CFRP under fatigue load.
• We studied the influence of damage degree level on strengthening efficiency.
• Theoretical model was established to predict the fatigue life.

An experimental and analytical study was conducted to further investigate the effectiveness of the carbon fibre reinforced polymer (CFRP) plates in extending fatigue life of steel structures. Different lengths of artificial cracks were introduced to represent different degrees of fatigue damage. The experimental results demonstrated that the CFRP patches could effectively slow down the crack growth and prolong the fatigue life. A theoretical model was developed to predict the fatigue life of tested specimens. Thereafter, a parametric study was carried out to investigate the fatigue behaviour of steel plates with a wider range of damage degrees. This study extends the understanding of CFRP repair at different stages of crack propagation and provides some useful suggestions for the strengthening method.