Ductility characteristics of fiber-reinforced-concrete beams reinforced with FRP rebars

To mitigate the corrosion problem caused by steel reinforcement, a study was initiated to develop a nonferrous hybrid reinforcement system for concrete beams by incorporating continuous fiber-reinforced-polymer (FRP) rebar and fiber-reinforced-concrete (FRC) containing randomly distributed polypropylene fibers. This paper describes the flexural performance of this FRP/FRC hybrid reinforcement system as well as FRP/plain concrete beams that served as references. Test results showed that the crack widths of FRP/FRC beams were smaller than those of FRP/plain concrete beams at the proposed service load. The compressive strains at the top fiber of concrete in FRP/FRC beams were larger than 0.004 due to the added polypropylene fibers. In addition, the ductility indices evaluating the FRP reinforced members were discussed. It is found that the ductility indices for all the tested beams were above the minimum requirement of 4. The addition of fibers improved the flexural behavior by increasing the ductility level more than 30%, when compared to the companion beam.

Research highlights
► This paper describes the flexural performance of a FRP/FRC hybrid reinforcement system.
► Crack widths of FRP/FRC beams were smaller than those of FRP/plain concrete beams.
► Compressive strains at the top fiber of concrete in FRP/FRC beams were larger than 0.004.
► Ductility indices increased by more than 30% with the addition of polypropylene fibers.
► Ductility indices of all the tested beams were above the minimum requirement of 4.