This project focuses on studying the behavior of steel reinforced and Glass Fiber Reinforced Polymer (GFRP) reinforced concrete beams in flexure. Due to the resistance against corrosion and high ultimate tensile strength, GFRP is constantly being proposed as an alternative to steel in local as well as global market. Therefore, deteriorating effect of corrosion on steel was simulated and observed on ABAQUS and GFRP RC beam was simulated on ABAQUS to determine the strength characteristics. Based on this, ACI 440.1 was used to design the concrete beams reinforced with GFRP and steel. These design calculations were used to model beam on ABAQUS such that control steel beam with no mass corrosion could be compared with increased mass corroded steel beams and similarly GFRP simulated beam could be compared with experimented beam. Analytical load-deflection curves were plotted. Five beams categorized according to the conditions were simulated. The model was designed to be deformed under two-point loading mechanism. Incremental load was applied on beam through which stress distributions were observed and load-deflection curves were obtained from ABAQUS. In the case of GFRP, similar curves with these parameters and simulated values were plotted, compared and analyzed. Simulated and literature curves were found to be consistent and in agreement with the behavior. Load carrying capacity of steel RC beams with 2 No.5 bars decreased about 22% with severe increase in mass corrosion. Whereas, experimented GFRP beams with 2 No.5 bars were found 77.5% of simulated GFRP RC beam. In the case of GFRP, the stiffness of beams derived from experimental values also compared well with the simulated values. Mass corrosion of steel RC beams gave decisive trend that increase in corrosion decreased the loads and deflections.