Performance evaluation of axially loaded BFRP-reinforced concrete members confined with hybrid helix-ties

These days, fiber-reinforced polymers (FRP) are being widely accepted in reinforced concrete structures because of their efficient structural performance and corrosion resistance. Efficient lateral confinement to the FRP-reinforced concrete compressive members is essential for their better performance due to the lower modulus of elasticity of basalt-FRP (BFRP) rebars. The combined usage of BFRP helices as transverse reinforcement in FRP-reinforced concrete members is not well examined in the body of literature currently in publication, especially in a variety of configurations. To better understand different transverse reinforcement configurations in FRP-reinforced concrete compressive members, this study is now underway. A combination of internal and external BFRP ties for dual restraints, an internal BFRP helix, external BFRP ties, and single BFRP ties are some of these designs. The investigation explores several aspects of the manufactured components, including the diameter of the longitudinal reinforcement, the type of material used for the transverse reinforcement, the vertical tie spacing, and various tie arrangements. In addition, a unique theoretical model that considers the contributions of both longitudinal and transverse BFRP rebars is put out to forecast the axial strength of the members that are created. When compared to the other two configurations, the results show that the application of BFRP combined helix-ties transverse reinforcement in FRP-reinforced concrete elements is the most effective in terms of core confinement and axial strength. Members with double BFRP ties and internal BFRP helix, as well as those with external BFRP ties, show enhanced axial strengths by 23% and 7%, respectively, in comparison to members with single BFRP ties. Secondary peaks in the load-deformation curves also show that members' ductility increases when the vertical distance between transverse reinforcement is reduced. The inclusion of FRP rebars in the study accounts for the notable higher accuracy of the proposed theoretical model as compared to earlier models, with only a 4% deviation from experimental results.