A Robust Finite Element Simulation of Circular Axially Loaded Members Reinforced with GFRP Bars and Spirals

The development of new generations of glass fiber-reinforced polymer (GFRP) bars has led to exponential growth in its application in bridges and marine infrastructures, where service life of over 100 years is desired. GFRP bars, predominantly used in flexural members, have seen limited application in reinforced compression members due to their low elastic modulus and compressive strength. Several full-scale experimental programs have been reported in recent years to explore the performance of GFRP bars as both primary and tie reinforcements in reinforced concrete columns. However, the effect of many parameters needs to be ascertained due to limited configurations of GFRP reinforcements in an experimental program. This study investigated circular reinforced concrete columns with GFRP longitudinal bars and spirals, focusing on key parameters affecting axial load behavior. The finite element model, validated against published experimental data, showed good agreement with axial load–displacement behavior. Parametric studies examined the effects of concrete strength, reinforcement ratio, spiral pitch, hoop spacing, spiral diameter, column diameter, and concrete cover. Concrete compressive strength, longitudinal reinforcement ratio, spiral diameter, spiral pitch, and reduced concrete cover were found to significantly enhance the ductility of the columns. Finally, the modeling results were compared with design capacity equations for GFRP bar-reinforced concrete columns provided in codes, design guides, and literature.