Effect of prestressed CFRP patches on crack growth of centre-notched steel plates

The fatigue performance of steel plates retrofitted with CFRP patches was investigated in this research. The test samples included three main types: reference centre-notched steel plates (unrepaired), repaired centre-notched steel plates using CFRP patches and repaired centre-notched steel plates using prestressed CFRP patches. In the specimens in which prestressed CFRP patches were used, the patches consisted of 1 or 2 layers of CFRP sheets and were prestressed up to 25% or 50% of their ultimate capacity. All specimens were then tested under uniaxial tensile fatigue. In order to measure the crack propagation rate, the beach marking method was used. Two different double-block fatigue loads were studied: one causing a stress range of 135 MPa and the other with a stress range of 150 MPa relative to the gross section of the steel plate.