Axial Compression Performance of Square Steel Tube Steel Fiber Concrete Columns

This study investigates the influence of microsteel fibers on the axial compressive properties of concrete‐filled square steel tubes (CFSSTs). Axial compression experiments and finite element analysis (FEA) were conducted on 10 specimens with varying steel fiber volume contents, steel tube wall thicknesses, and slenderness ratios to examine the failure modes, load–displacement curves, and ultimate bearing capacities of steel fiber‐reinforced concrete‐filled square steel tubes (SCFSSTs). Parameters such as force, ductility, energy dissipation capacity, and Poisson's ratio were assessed. The experimental results indicated that the addition of microsteel fibers can delay damage to the core concrete and buckling of the steel tubes. Specifically, increasing the volume content of steel fibers from 0% to 1.2% enhanced the ductility coefficient by 70%. Concurrently, both the energy dissipation and bearing capacities were improved as the steel fibers enhanced the postpeak performance of the CFSST. FEA was performed using the ABAQUS software to establish a steel fiber model. The FEA results were found to be consistent with the experimentally obtained load–displacement curves, and a parameter analysis was performed for further study. Finally, the applicability and accuracy of the four current international codes for calculating the ultimate bearing capacity of SCFSST were evaluated.