experimental study of circular concrete column confined with hybrid frp-steel tube, under axial load

This study investigates the axial compressive behavior of circular concrete columns confined using three methods: steel tube confinement, frp confinement, and hybrid frp–steel tube confinement. specimens were designed with similar confinement ratios to allow fair evaluation of their mechanical performance. experimental results showed that while the type of confinement had little effect on the initial stiffness, it significantly influenced the post-peak behavior. steel confinement offered the highest strength and ductility, while frp confinement increased ultimate strain but failed abruptly due to brittle rupture. the hybrid system exhibited a staged failure mechanism with the improved confinement efficiency and a balance between strength and ductility. stress–strain curves, volumetric strain trends, and tangent poisson's ratio analyses highlighted the superior performance of the hybrid systems. the findings suggest that hybrid frp–steel confinement is a promising solution for enhancing both strength and deformation capacity in reinforced concrete columns, especially in seismic or high-performance structural applications.