Simple and efficient finite element modeling of reinforced concrete columns confined with fiber-reinforced polymers

• A simple and accurate frame element is presented for modeling RC columns confined with FRP.
• Advanced material constitutive models are used for steel and confined/unconfined concrete.
• The adopted FE can model failure due to concrete crushing, steel yielding and FRP rupture.
• Numerical and experimental results are compared in terms of strength and deformation.
• Numerical results are in excellent agreement with experimental results from the literature.

This paper presents a frame finite element (FE) that is able to accurately estimate the load-carrying capacity and ductility of reinforced concrete (RC) circular columns confined with externally-bonded fiber-reinforced polymers (FRP). This frame FE can model collapse mechanisms due to concrete crushing, reinforcement steel yielding, and FRP rupture. The adopted FE considers distributed plasticity with fiber discretization of the cross-sections in the context of a force-based formulation, and uses advanced nonlinear material constitutive models for reinforcing steel and unconfined, steel-confined, and FRP-confined concrete.The adopted frame FE is validated through a comparison between numerical simulations and experimental results available in the literature of the load-carrying capacity of FRP-confined RC columns subjected to axial load only, and both axial and lateral load. The adopted FE is suitable for efficient and accurate modeling and analysis of FRP-confined RC columns, and thus it represents a step toward enabling analysis of real-world large-scale structures containing FRP-confined RC columns, for which more accurate three-dimensional models could be computationally prohibitive.