Finite element analysis of concrete columns reinforced with fiber-reinforced polymer (FRP): Load-strain behavior

This study examines the axial strength of circular concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars and spirals. Although fiber-reinforced polymer (FRP) bars are commonly used for flexural and shear strengthening, their effectiveness as longitudinal reinforcement under axial compression is not as well understood. Using Abaqus finite element software, the study simulates twelve large-scale reinforced concrete (RC) columns previously tested under concentric axial loads. The concrete damage plasticity (CDP) model was used to simulate concrete behavior, accounting for both tensile and compressive damage. The numerical results showed good agreement with experimental data, with a load capacity ratio of 0.92. The findings indicate that GFRP-reinforced columns achieved similar axial capacities to conventional steel-reinforced ones, with longitudinal GFRP bars contributing 5-10% of the total load. Additionally, closely spaced, smaller-diameter GFRP spirals were more effective in enhancing ductility and confinement than larger, widely spaced spirals. The study confirms that numerical models can reliably predict the axial strength of GFRP-reinforced columns and suggests that excluding GFRP bar contributions in design may underestimate column capacity. Future research should focus on varied loading conditions, GFRP material properties, and cross-sectional dimensions to improve model accuracy and support broader design applications. Key words: Circular fiber-reinforced polymers concrete columns, finite element analysis, axial load, glass fiber-reinforced polymers bars, numerical modeling, fiber-reinforced polymers.