Analytical Framework for Evaluating the Nominal Flexural Moment Capacity of FRP-RC Beams for Sustainable Infrastructure Applications

Abstract

Fiber-reinforced polymer (FRP) bars have gained growing attention as internal reinforcement for reinforced concrete (RC) members because they are resistant to corrosion and can improve the long-term durability of concrete infrastructure. This durability advantage may also support more sustainable construction by reducing maintenance and rehabilitation needs over the service life of RC members. This study presents a strain-based sectional analysis method for estimating the nominal flexural moment capacity of RC beams reinforced with FRP bars. The formulation is established from the conditions of strain compatibility and internal force equilibrium, while accounting for the compressive behavior of concrete and the tensile response of FRP reinforcement through their respective material constitutive models. An iterative solution scheme is used to identify the neutral axis position, section curvature, and controlling failure mechanism, such as concrete crushing or FRP rupture. To assess the validity of the proposed approach, a database of 29 experimentally tested beam specimens reinforced with glass fiber-reinforced polymer (GFRP), carbon fiber-reinforced polymer (CFRP), and aramid fiber-reinforced polymer (AFRP) bars was assembled from prior studies, and the calculated nominal moment capacities were evaluated against the reported test results. Overall, the proposed method provides a consistent framework for predicting both the nominal flexural strength and failure mode of RC beams reinforced with various FRP bar types and reinforcement ratios. The proposed method showed good agreement with the experimental results, with a mean test-to-predicted moment ratio of 1.04 and a coefficient of variation (COV) of 9%. However, the model was validated using a limited database and should be further checked for wider beam configurations and material properties.