Predicting flexural capacity of concrete beams reinforced with GFRP bars and strengthened with CFRP sheets

Abstract

FRP material has proven to be a proper replacement for the traditional steel reinforcement having superior mechanical properties and high tensile strength. FRP is a highly durable material being nonmagnetic and noncorrosive material. Such materials are effectively used as a construction material that is specially situated in an aggressive environment. This paper investigates the performance of concrete beams reinforced with glass fiber reinforced polymer bars (GFRP) and the applicability of carbon fiber reinforced polymer (CFRP) sheets as a strengthening regime for such systems. With this intent, a total of four 2.4m RC beams were tested. All beams were reinforced with GFRP bars in flexure and shear. Two served as reference beams, and the remaining two were strengthened with CFRP wrap fabric. It was found that the contribution of GFRP bars in load carrying capacity for beams strengthened by CFRP sheet is not as efficient as when CFRP is used with steel rebars. This could be attributed to the difference in stress-strain relationship of the GFRP, CFRP, and steel which are distinctly different from each other. While CFRP and steel have similar modulus values, the modulus value for GFRP is substantially low. Finally, a contribution factor (λ) for predicting the flexural capacity for such systems as per ACI 440 proposal.