Experimental and numerical study on the axial compressive behavior of steel tube‐reinforced self‐compacting concrete columns

Abstract This study investigates the axial compressive behavior of self‐compacting concrete (SCC) columns reinforced longitudinally with internal steel tubes as an alternative to conventional steel bars. Ten SCC columns were tested under monotonic axial compression, including one reference specimen with steel bars and nine specimens reinforced with steel tubes of varying thicknesses (1.5, 2.0, and 3.0 mm), tie spacings (100, 150, and 200 mm), and cross‐sectional shapes (square and rectangular). The results demonstrate that increasing steel tube thickness significantly enhances confinement efficiency, leading to higher axial load capacity, stiffness, and deformation capacity. The specimen with a 3 mm tube thickness exhibited the best performance, achieving up to a 44% increase in peak load, a 52% increase in stiffness, and a 66.5% enhancement in deformation capacity compared with the reference specimen. Rectangular columns exhibited 7%–10% lower peak loads and 10%–20% lower stiffness than square columns under comparable confinement conditions due to less uniform stress distribution, despite higher reinforcement ratios. Additionally, a validated finite element model (FEM) developed in ABAQUS was used to conduct a parametric study. The FEM results analysis revealed that increasing concrete compressive strength enhances both stiffness and peak load, while increasing the steel tube yield strength primarily improves ultimate capacity and ductility with minimal effect on initial stiffness. This study provides a practical and efficient solution for enhancing the performance of reinforced concrete (RC) columns, with potential applications in buildings, bridges, and other structural systems requiring improved strength and ductility.