Abstract
The use of concrete-filled steel tube columns (CFST) has gained prominence in modern construction. Comprehensive studies have been performed on mass CFST columns subjected to axial loading. Given the reputable performance of reinforced concrete elements, the addition of reinforcement is expected to improve a composite column’s overall performance under axial loading. By means of a numerical analysis, this research will investigate the performance and behaviour of reinforced lightweight aggregate concrete-filled steel tube (RLWCFST) columns under axial compression.
A validated numerical model will assess data produced from former experimental work carried out, which comprises eighteen specimens with three length-to-diameter (L/D) ratios (short, medium and long) and two diameter-to-thickness (D/t) ratios (thin and thick). The data reveals graphic results with respect to the compression loading versus displacement curves, and the failure modes of the eighteen specimens. These results will be compared and discussed in relation to the predictions of Eurocode 4 (EC4) design specifications which include design checks on member slenderness, shear, cross-sectional and bending resistance. The discussion of the numerical results will provide guidelines on control variables and parameters that require cognisance when consulting the EC4 design specifications.
By way of the numerical analysis and experimental data, the reinforcement steel would improve the mechanical behaviour of lightweight concrete (LWC) and increase the combined compression and bending resistance, shear capacity and ductility of the composite column. The failure modes of the specimens are influenced by the behaviour of the reinforced and unreinforced LWC and the geometric properties of the steel tube. Reinforcement steel merged with thinner steel tubes provide exceptional structural integrity. Essentially, the introduction of reinforcement steel can significantly enhance the overall performance of a composite column. Furthermore, the use of larger diameter steel bars is more favourable than thick steel tubes and can enhance the ductility and compression resistance of short, medium and long columns.