Comparative Analysis of RC Beams Torsional Performance: FRP Wrapping Versus NSM-FRP Bar Strengthening

The utilization of fiber-reinforced polymers (FRP) as strengthening agents has been widely employed to improve the flexural and shear strength of reinforced concrete (RC) beams.However, research on enhancing the strength of reinforced concrete (RC) beams under torsional forces through the application of fiber-reinforced polymer (FRP) wrapping or Near-Surface Mounted (NSM)-FRP is few.This work utilizes ABAQUS/CAE version 2019 finite element (FE) software to conduct nonlinear numerical simulations.The purpose is to investigate the torsional-flexural behavior of reinforced concrete (RC) beams that have been reinforced with either fiber-reinforced polymer (FRP) wrapping or near-surface mounted (NSM) FRP bars.Comparing computational and experimental models showed that the experimental model's final torque and angle of twist averaged 1.016 and 0.89 for the numerically investigated components.The results show that changing the inclination angle of the bar or sheet from 90 to 45º has a significant impact on the ultimate torque Tu, where the changing of the inclination angle from 90 to 45º increased the Tu by about (14.13, 13.39 and 13.83%) for beams with an inclination angle of 45º (with CFRP sheets spacing of 150 mm, with NSM bars spacing of 200 mm, and with CFRP sheets spacing of 150 mm and longitudinal CFRP sheet ) with respect to the similar beam for each one but with inclination angle of 90º , which means that changing the inclination angle of the bar or sheet from 90 to 45º increases the torsional stiffness of the beam.Longitudinal CFRP or NSM reinforcement increases beam torsional and bending stiffness.Reducing the NSM bar gap increases beam torsional and shear stiffness.