Numerical simulation and design of circular steel-reinforced concrete-filled steel tubular short columns under axial loading

This paper presents a computational model for determining the axial responses of circular Steel-Reinforced Concrete-Filled Steel Tubular (SRCFST) short columns. A novel confinement model is formulated for the concrete-core that is effectively confined by the external circular steel tube and the embedded steel section. The modeling scheme of confinement is programmed in the mathematical model that utilizes the fiber element discretization of column cross-sections. The numerical predictions are verified by experimental measurements and results obtained from the finite element analysis, demonstrating the accuracy of the modeling technology. In addition, existing concrete confinement models for concrete in circular Concrete-Filled Steel Tubular (CFST) columns are assessed. The new confinement model is shown to be superior in replicating the responses of SRCFST columns. The influences of design parameters on the column's performance are numerically investigated and the importance order of these parameters is determined by a sensitivity analysis. The study not only examines the validity of current design standards in determining the axial load capacity of SRCFST columns but also proposes a new design formula. The proposed confinement model can be employed in numerical procedures for the inelastic simulation of SRCFST columns and the design formula is suitable for use in practical design.