Interaction between CFRP-repair and initial damage of wide-flange steel beams subjected to three-point bending

This paper presents the interaction between carbon fiber reinforced polymer (CFRP) composites and the level of damage in steel beams. An experimental program is conducted with three different sizes of notches at midspan of the beams to simulate initial damage prior to repair. A three-dimensional finite element analysis (FEA) is conducted to predict experimental behavior. Unlike existing predictive models that assume perfect bond between CFRP and steel substrate, the proposed modeling approach explicitly accounts for the bond–slip behavior of CFRP–steel interface. CFRP-repair improves the load-carrying capacity of damaged beams that have failed by crack propagation across the steel section with wide opening of the notch. For repaired beams; stress concentrations at a damage location result in local debonding of the CFRP sheet, followed by complete debonding failure of the sheet. These failure modes are found to be independent of the level of initial damage (notch depth). CFRP-repair delays crack-formation of the repaired beams; however, such an effect is not significant once a crack propagates towards the upper flange. The level of initial damage influences debonding propagation rates of the CFRP. Two distinct bond–slip responses of the CFRP–steel interface are experimentally observed.