A comparative review on the structural behaviour of GFRP rebars with conventional steel rebars in reinforced concrete columns

FRP reinforcement bars are advantageous in environments prone to corrosion, such as coastal areas, and in electromagnetically sensitive zones. They are an appealing alternative to steel-reinforced concrete structures, which require frequent maintenance. Despite their benefits, the behaviour of FRP-reinforced concrete columns is complex and less explored than their use in beams and slabs, limiting broader application. This paper aims to provide insights into the structural characteristics of concrete columns reinforced with Fiber Reinforced Polymer (FRP) rebars, specifically GFRP bars, as alternatives to steel bars. It examines the influence of parameters such as aspect ratio, concrete type and grade, slenderness ratio, and reinforcement percentage on the strength and ductility of GFRP RCC columns under axial and eccentric loads. Design equations and numerical methods for predicting load-carrying capacity are summarised. The literature review reveals that GFRP RCC columns have 80–100% of the strength of steel RCC columns under concentric loading and 60–103% under eccentric loading, with a higher ductility index than steel RCC columns by an average of 17.4%. For NSC and HSC columns, GFRP bars contribute about 50% of the axial load-carrying capacity compared to steel bars. From the literature review in predicting the design load-bearing capacity of GFRP-RCC columns, it has been found that using the modulus of elasticity to determine the contribution of FRP longitudinal bars and employing concrete compressive strength rather than axial strain in FRP longitudinal bars contribution, yields more accurate predictions.