Global stability capacity of partially encased composite columns with cruciform-shaped section under axial compression

This paper undertakes a test investigation and finite element (FE) analysis of the stability behavior of partially encased composite (PEC) columns with cruciform-shaped sections. Two PEC column specimens with the same geometric size were tested under axial compression loading, and the difference between the specimens is that the main steel components (MSCs) made of solid-web steel and castellated steel, respectively. The test results show that the two columns exhibited similar failure modes: concrete crushing and global flexural instability. Furthermore,the capacities of both columns were found to be smaller than the corresponding theoretical axial capacities of the composite column section. The test and FE results show that the bearing capacity of the PEC columns with solid-web MSCs is higher than that of the PEC columns with castellated MSCs. The size of the web openings exerts a considerable detrimental impact on the compressive capacity of the PEC column, while the shape and spacing of the openings have little influence on the capacity. In addition, design equations were proposed to predict the stability capacity of the cruciform-shaped section PEC column with both solid-web MSCs and castellated MSCs, in the equations, the castellated MSCs were simplified as the lattice columns with batten plates. •Propose a novelty cruciform section partially encased composite (PEC) column with castellated main steel component (MSC).•Investigate the influence of the web openings by comparing the two PEC columns with solid-web MSC and castellated MSC.•Establish the design equations of the axial compressive stability capacity of the two cruciform section PEC columns.