Shape and size effects on compression performance of concrete-filled steel tube

Abstract The present study aims to maximise the compression performance of Concrete-filled steel tube (CFST) columns using different shapes and sizes. CFST columns have been used in many parts of the world for their outstanding performance over traditional plain concrete structures in higher load-carrying capacity, ductility and toughness. Although previous studies focused on the CFST column design under different loading conditions, there is no clear guidance on the effect of geometrical properties (shape and size) on the compression performance of CFST columns. The present research developed a validated numerical model to examine the load-carrying capacity of CFST columns in compression with different geometrical properties. The results show that the circular column carried a 51.56% higher axial load than the square column. However, when the column height increased from 360 to 1000 mm, the load-carrying capacity of the circular column decreased by 14.53%, compared to a 2.22% reduction for the square column. Furthermore, variations in thickness ratios (width-to-thickness ratio ( H / t ) and diameter-to-thickness ( D / t )), slenderness ratios, and aspect ratios (width-to-breadth ratio ( H / B )) increased the load-carrying capacity by 40.60% for square columns and 22.47% for circular columns when using a 10 mm steel tube thickness. These findings provide useful insights for optimising CFST column design to achieve improved structural performance under axial compression.