Performance enhancement of externally bonded reinforced concrete beams with 3D hooked-end steel fibres

Abstract

Studies on externally bonded fibre reinforced polymer (FRP) strengthened/laminated reinforced concrete (RC) beams have been exhaustively carried out in recent past decades in various countries. And the method has been found effective in various aspects compared to other earlier structural strengthening methods. From the reported studies, the load-carrying capacity of such beams found often limited due to premature debonding types of failure of FRP composite. The above phenomenon also considerably affects the ductility properties of the beams. Enhancement of the flexural capacity of FRP strengthened beam, and to overcome the ductility depletion on the above-said beams is need of an hour. This paper proposes a technique in which short, discrete hooked-end steel fibres are added into the concrete mix and then strengthened with GFRP laminates to counteract the above enhancements bilaterally. An experimental investigation on externally GFRP bonded RC beams with steel fibres was conducted based on the above. Three different types of beams, namely, an unstrengthened RC beam; one GFRP strengthened RC beam; three GFRP strengthened RC beams added with hooked-end steel fibres in three different volume contents (0.5%, 1.0%, and 1.5%), were considered in this study. The parameters considered in this study are load, deflection, ductility property, and mode of failure of the beams. The finite element analysis (FEA) based beam models were developed using the ANSYS software and validated. The addition of steel fibres pats the potential of GFRP laminate and enhances the overall performance of strengthened beams to a greater extent.