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

Carbon fibre reinforced polymers (CFRPs) are now accepted in the retrofit and repair industry as extremely efficient and capable of compensating for the loss of structural integrity, resistance and serviceability. Nevertheless, the application of these materials can be improved in various ways to meet structural requirements. One of the methods of improving the usage of CFRP sheets and laminates and benefiting from their full capacity is prestressing. 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. (C) 2014 Elsevier Ltd. All rights reserved.