A Comparative And Parametric Investigation Of Circular And Square CFST Columns Using Finite Element Analysis

Abstract

Concrete-filled steel tubular (CFST) columns combine the compressive resistance of a concrete core with the tensile capacity, ductility, and confinement supplied by an external steel tube. This study presents a comparative and parametric finite-element investigation of circular and square CFST columns using ANSYS Mechanical APDL. Three-dimensional nonlinear models employed SOLID65 elements for concrete and SHELL181 elements for the Fe250 steel tube. Concrete grades M25, M30, M55, M60, and M80 were defined using the material values reported in the study. The analytical programme examined cross-sectional shape, concrete grade, tube dimensions, and diameter-to-thickness or breadth-to-thickness ratios. Eurocode-based calculations produced design buckling resistances of 1,355 kN for the representative circular column and 1,675.629 kN for the representative square column. Across the parametric series, reducing D/t or B/t increased load capacity because thicker steel walls improved confinement and delayed local buckling. For the compared CFST models, circular columns exhibited lower deformation and stress than square columns at every reported load level; at 4,000 kN, deformation was 2.61 mm for the circular model and 9.89 mm for the square model. Comparison with plain concrete further demonstrated the benefit of steel confinement. The results identify cross-sectional geometry, concrete strength, and tube slenderness as the dominant parameters controlling CFST capacity and deformation.