Parametric finite element analysis of flexural behavior in FRP-reinforced beams

The increasing use of fiber-reinforced polymer (FRP) bars as internal reinforcement offers a corrosion-resistant and lightweight alternative to steel in concrete structures; however, their linear-elastic behavior often limits ductility and crack control. To address this challenge, the combination of FRP reinforcement with advanced and sustainable concrete types such as fiber-reinforced and alkali-activated concretes, has emerged as a promising yet underexplored solution. This study investigates the flexural behavior of beams made from four concrete types: Portland Cement Concrete (PCC), Alkali-Activated Concrete (AAC), Fiber-Reinforced Concrete (FRC), and Fiber-Reinforced Alkali-Activated Concrete (FRAAC), all reinforced with Glass FRP (GFRP) bars. A detailed nonlinear finite element model was developed using ABAQUS software, employing 3D solid (C3D8R) elements for concrete and truss (T3D2) elements for FRP bars with embedded-region constraints. The Concrete Damaged Plasticity (CDP) model simulated concrete behavior, while FRP reinforcement was modeled as linear-elastic up to rupture. The model was calibrated and validated against experimental results, achieving high accuracy in predicting load–deflection responses and failure modes. A comprehensive parametric study of 224 simulations examined the influence of FRP type, reinforcement ratio, and beam depth. Results showed that CFRP bars yielded the highest load increase (up to 90%), while increasing tensile reinforcement ratio (0.5–3.28%) enhanced capacity by 11–132% and reduced deflection by 54%. Increasing beam depth (250–400 mm) improved load capacity by up to 172%, with compression reinforcement contributing less than 11%. The findings highlight the significance of integrating FRP reinforcement with sustainable fiber- and geopolymer-based concretes, demonstrating the capability of finite element analysis in optimizing hybrid high-performance structural systems.