Effect of hybrid fibre reinforcement on capacity of reinforced concrete beams

Abstract

This study evaluates the flexural behaviour of reinforced concrete beams strengthened by hybrid fibre reinforcement. Hybrid fibre reinforcement prepared in two ways is considered: using a hybrid fibre sheet and a hybrid fibre plate. Experimental research on the feasibility and applicability of strengthening effects due to hybrid fibre plate and hybrid fibre sheet in reinforced concrete beams has been carried out. Each of control and seven specimens strengthened by hybrid fibre sheet and hybrid fibre plate was tested by four-point bending tests using a hydraulic universal testing machine. For hybrid fibre sheet specimens, debonding between the adhesive and the beam that propagates from the end of the plate has been observed in experiments. According to the test results, reinforced concrete beams strengthened by hybrid fibre reinforcement showed approximately 60–200% higher load capacities and strengths relative to unreinforced specimens. In addition, all reinforced beams showed an ideal failure pattern, with the presentation of ductile behaviour after yielding of the reinforcing bar. More specifically, in the cases of reinforced concrete beams reinforced with hybrid fibre plate, no difference according to the puttying method was apparent, since the hybrid fibre plate-retrofitted reinforced concrete beams reinforced using epoxy injection and adhesive bonding showed similar failure patterns.