Flexural strengthening of RC beams with externally bonded CFRP plate: experimental study on shear-peeling debonding

This paper reports on experimental investigations of externally bonded carbon fibre reinforced polymer (CFRP) plate debonding behaviour using beam specimens flexurally strengthened by CFRP plates induced by a relative vertical displacement imposed on the two sides of a shear crack in each beam under a four-point bending load. Three specimens, two of which were control specimens to confirm shear failure and one of which was a shear-deficient test specimen under high-level fatigue load, were strengthened with bottom-bonded CFRP plate and side-wrapped CFRP sheet. The variables investigated during the experimental programme were the displacement between the concrete substrate and the CFRP plate, the strain distribution of the CFRP plate and the local bond stress–slip relation. The test results showed the effectiveness of shear–peeling debonding in CFRP plates along with shear crack width opening based on fatigue load and local debonding with peeling off as an important factor affecting the fatigue life by shear failure in this case.