Behaviour of square hollow steel tubular (SHST) stub columns after elevated temperature

To investigate the behaviour of square hollow steel tubular (SHST) stub columns after elevated temperatures under axial compression, a total of 51 specimens were tested, including 48 SHST stub columns after elevated temperatures and 3 SHST stub columns at ambient temperature, of which 12 SHST stub columns were carried out load-strain tests. The main parameters explored in the test include temperature ranging from 400 °C to 1000 °C, thickness (2.0 mm, 3.0 mm, 4.0 mm) and high temperature duration (1.0 h, 1.5 h, 2.0 h, 2.5 h). This paper presents the failure modes, load-bearing capacity, load-strain curves, load versus displacement curves, initial stiffness at elastic stage and ductility of the specimens. Results show that failure modes of SHST columns at ambient temperature and elevated temperature follow similar pattern. It was found, in general, that temperature and thickness have significant influence on the behaviour of SHST columns; however, high temperature duration has negligible influence on the behaviour of SHST columns. Based on the experimental results, a formula is proposed to calculate the load-bearing capacity of SHST stub columns after elevated temperatures. It is evident from the comparisons between the results calculated from the formulas and the experimental results that the calculation gives results with reasonable accuracy. Finite element models having the same dimensions of test specimens were simulated to compare the finite element analysis results with experimental results. It can be seen from the comparison that finite element analysis results were in good agreement with experimental results.