Description
Fibre Reinforced Polymer (FRP) materials are widely used to strengthen Reinforced Concrete (RC) structures due to their high mechanical and durability properties with respect to traditional techniques. However, intermediate crack debonding (ICD) failure limits the effectiveness of strengthening RC beams in flexure with externally bonded (EB) FRP laminates. Anchorage of the FRP can mitigate this premature debonding and enhance the efficiency of FRP strengthening.
Hybrid Bonding (HB) FRP emerged as a viable method for delaying/preventing debonding of EB FRP RC beams. HB combines adhesive bonding from EB with mechanical fastening through metallic plates, increasing resistance to debonding. Previous research explored the bonding capacity of the HB connection using FRP sheets in single-shear tests, but only a few simplified approaches for predicting the bending capacity of strengthened beams have been developed.
In this paper, the feasibility of HB systems to delay ICD debonding of RC flexural elements strengthened with CFRP pre-cured laminates is assessed through experimental and theoretical studies. For this purpose, three RC beams strengthened with CFRP are tested, one using EB technique and two using HB, with different anchor spacings. Results include load-deflection response, flexural capacity and failure mode, compared to literature provisions. Results show that the HB technique consistently improves the flexural performance of the beam in all considered cases.
