Strength and ductility behaviour of FRC beams strengthened with externally bonded GFRP laminates

Abstract

The repair and rehabilitation of structural members are perhaps one of the most crucial problems in civil engineering applications. One of the advanced techniques of strengthening the reinforced concrete members is done by fiber-reinforced polymer composites. FRP is very effective to repair and strengthen the structural members that have become structurally weak over their life span. FRP repair system provides an economically viable alternative to traditional repair systems and materials. This experimental study focuses on the flexural strengthening of fiber reinforced concrete beams externally bonded with FRP laminates of different thicknesses. Six beams were cast for the study and tested under a four-point bending system. Out of which two beams were served as a control beam, one beam was considered as a reinforced concrete beam and the other was fiber reinforced concrete beam. The fibers used in this investigation were steel fiber. The beams were strengthened with GFRP of 3 mm and 5 mm of woven roving type. The study parameters of this investigation included yield load, ultimate load, deflection, yield load deflection, ultimate load deflection, deflection ductility, energy ductility, and the beam was found to be very effective in the load-carrying capacity, deflection, and ductility when compared to the control specimen. The fiber-reinforced concrete beam exhibit an increase in ultimate deflection by 79.3% when compared to the control specimen. GFRP strengthened beams showed an increase in ultimate deflection by 18.75% to 94.06%. GFRP strengthened fiber reinforced concrete beams showed an increase in ultimate deflection by 7.8 to 13.125%. GFRP strengthened beams showed an increase in ultimate deflection by 54.7% to 81.88%. GFRP strengthened fiber reinforced concrete beams showed an increase in ultimate load-carrying capacity by 36.9% to 48.7%. The ductility for the specimens increases by 1.27% to 1.34%, compared to the controlled specimen.