Use of Bore-Epoxy Anchorage System with CFRP Sheets for Shear Strengthening of RC Beams

Abstract

Shear failure in reinforced concrete (RC) beams is brittle and undesirable type of failure. This paper investigates the use of bore-epoxy as an anchorage technique for CFRP sheets used as externally bonded shear strengthening reinforcement. Five shear deficient RC beams were cast, one was used as a control (C), one was strengthened with two side CFRP sheets as EBR without anchorage and used as a second control or reference beam (S-EBR) and the remaining three were strengthened using two side CFRP sheets as EBR with bore-epoxy anchorage of different bore diameters (15 mm, 25 mm, 35 mm). The RC beam specimens were tested under four point bending. Load-deflection and load-strain values were recorded. The results showed that the bore-epoxy anchorage system delayed the CFRP sheets de-bonding and increased the shear capacity of the tested specimens by up to 10% compared to the S-EBR control beam and by up to 56% compared to the unstrengthen control beam. The load-deflection curves showed a considerable increase (up to 63.5%) in the deflection of the RC beams strengthened with bore-epoxy anchorage compared to the control beam resulting in a more ductile failure. The failure modes of the tested RC beams varied with the strengthening and the anchorage system used, but they were predominately delamination for the beams strengthened with externally bonded CFRP sheets on bore-epoxy anchorages.