Axial compression behavior of STCLAC short columns

In this paper, the axial compression behavior of steel tube confined lightweight aggregate concrete (STCLAC) columns is studied by combining test research, finite element analysis (FEA), and theoretical derivation. The experimental parameters include the diameter-to-thickness (D/t) ratio, yield strength, and the contact materials. The results revealed that when the D/t ratio equals or exceeds 19.0, it affects the axial compression performance of STCLAC columns; conversely, the effect can be ignored. The yield strength also notably influences the ultimate capacity of STCLAC columns. Furthermore, the longitudinal forces of steel tubes in STCLAC columns, which use polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC), are later than those columns using oil, resulting in decreased specimen stiffness. Then, a three-dimensional FEA model for STCLAC columns was established and confirmed its accuracy. The influence of D/t ratios, LAC compressive strength, and friction coefficients on the bearing capacity of STCLAC columns is studied through parameter analysis. Finally, formulas are presented for calculating the transverse and longitudinal stresses in the steel tube of STCLAC columns at ultimate loads and predicting the ultimate load-bearing capacity.