Flexural behavior and deflection prediction of concrete beams reinforced with AFRP and CFRP bars

Due to the low elastic modulus of fiber reinforced polymer (FRP) materials, concrete members reinforced with FRP bars show greater deflections than members reinforced with steel reinforcement. Deflection is an important factor to consider in the serviceability of floor members. In this study, flexural tests of both AFRP and CFRP reinforced concrete beams were performed with the reinforcement ratio and concrete compressive strength as the main parameters. The test results indicate that the flexural capacity and stiffness increase in proportion to the reinforcement ratio and compressive strength of concrete as expected. In addition, the test results are compared with deflection calculations based on existing proposed equations for the effective moment of inertia. This comparison demonstrates that the ACI 440.1R-06 (ACI Committee 440 2006) approach for FRP reinforcement underestimates deflection of AFRP reinforced concrete, while a more rational approach proposed by Bischoff (2005) is able to predict deflections reasonably well for concrete reinforced with both types of FRP reinforcement investigated (AFRP and CFRP) and for steel reinforcement.