An Investigation on the Contribution of FRP Longitudinal Rebar In RC Columns

Concrete columns were previously only reinforced with steel reinforcements. Nowadays, with the introduction of FRP rebar, these reinforcements are used in concrete elements as a proper replacement for steel reinforcements, especially in corrosive environments such as marine environments. But the use of this type of reinforcement in columns of concrete structures faces uncertainties, so that the various international codes do not take into account the effect of this type of rebar, or they do not allow them. Due to the elastic behavior of FRP reinforcements and their high ultimate strain as compared to the ultimate strain of concrete, these rebar are generally not contributed to concrete in concrete columns. In this study, using mathematical equations and parametric study as well as finite element software, the contribution of FRP reinforcements has been investigated and it has been shown that neglecting FRP reinforcement in some cases can lead to very conservative results in terms of capacity. The type of FRP reinforcement and the percentage of longitudinal reinforcement have the greatest impact on the contribution of these reinforcement to the compressive strength of the column so that this increase can form up to one quarter of the compressive capacity of the column.