Structural response of GFRP strengthened hybrid fibre reinforced concrete beams

Abstract

This paper investigates the structural response of hybrid fibre reinforced concrete (HFRC) beams strengthened with glass fibre reinforced polymer (GFRP) laminates. For this six different types of beams were casted namely; a reinforced concrete (RC) beam act as control beam, strengthened RC beam and four strengthened hybrid fibre reinforced concrete (HFRC) beams having (70:30) proportion of basalt and polyolefin fibres with 0–2% of total volume fraction. The beams were strengthened with GFRP laminates of 5 mm thickness at tension face. All the beams were tested under four point bending with an effective span of 900 mm. The study parameters included service, yield and ultimate loads, moment–curvature, ductility and failure modes. From the test results, it was found that, ultimate load of ‘strengthened HFRC beam’ at fibre volume fraction 1.5% increased by about 98.39 and 48.67% compared with that of ‘control beam’ and ‘strengthened RC beam’. In addition, positive interaction amongst basalt and polyolefin fibres subsequently reduce the propagation of cracks, which leads to increase in interfacial bond between concrete surface and FRP laminates, there by the failure modes were changed from brittle to ductile. The experimental results show that strengthened RC beams with a 1.5% of basalt and polyolefin fibres has significantly improved the overall performance of beams.