Key Factors Affecting the Performance of Square Concrete-Filled Steel Tube Columns: A Comparative Analysis of International Design Codes

This study investigates the structural behavior of concrete-filled square steel tube (CFST) columns under axial loading using finite element analysis (FEA) in ANSYS. A comprehensive validation process ensures the accuracy of the numerical models by comparing them with experimental results. Key parameters influencing CFST performance, including concrete compressive strength, steel yield strength, and slenderness ratio, are systematically examined. Findings indicate that concrete compressive strength has the most significant effect on load capacity, with an increase of up to 288% observed when the strength is raised from 25 MPa to 100 MPa, particularly in columns with lower slenderness ratios. In contrast, steel yield strength has a relatively lower impact, especially for slender specimens where local buckling governs failure. Additionally, this study assesses the accuracy of international design codes in predicting CFST axial capacities. Results show that the Egyptian Code (ECP 205-2007) tends to overestimate failure loads, whereas the AISC 360-16-2016 provides the most accurate predictions, closely matching FEA results. The AS/NZS 5100.6-2017 code also demonstrates a reasonable level of accuracy. These findings contribute to a better understanding of CFST structural behavior, highlighting the need for improved design provisions that account for key influencing parameters.