Axial Behavior and Design of High-Strength Rectangular Concrete-Filled Steel Tube Long Columns

Due to the lack of adequate research and deep understanding of high-strength concrete-filled steel tube (CFST) long columns, the current specifications cannot provide the available guidelines and design equations. To address the gap, this paper investigates the axial behavior of high-strength rectangular CFST long columns by experimental database, finite element analysis, and theoretical modeling. Firstly, the experimental database including 74 specimens for high-strength rectangular CFST long columns was compiled. Then, the detailed 3D non-linear finite element method (FEM) models were developed and verified for parametric studies. The effects of steel yield stress, concrete strength, section slenderness ratio and slenderness ratio on the ultimate strength and slenderness reduction factor were investigated. Finally, the possibility of extending the current design equations in different specifications was evaluated.