Design Proposal for Concrete Cover Separation in Beams Strengthened by Externally Bonded Tension Reinforcement

摘要

Existing experimental observations have shown that the application of externally bonded reinforcement (steel plate, FRP laminate, overlay, etc.) to strengthen RC structures can lead to brittle failures involving debonding of the external reinforcement before the design load is reached with classical failure modes. The design approach to determine the strengthening material and its area should avoid these premature failures. In this study, an analytical model developed for the overlay strengthening by the authors is firstly proved to be applicable for the steel plate or FRP laminate strengthening by comparing the analytical and experimental failure load as well as the failure mode of the strengthened beams reported in the literature. Then the main parameters involved in the process of concrete cover separation are identified and a simple criterion is proposed for prediction of premature failure.