Size effect of axial compressive bearing capacity of high-strength concrete filled high-strength square steel tubular short columns

The existing research on the size effect of concrete filled steel tubular short columns under axial compression are mostly focused on circular sections and ordinary-strength members, while the study on size effect of highstrength concrete filled high-strength square steel tubular short columns is relatively limited. In this paper, a multi-scale modelling method was proposed in order to study the size effect of axial compressive capacity of high-strength concrete filled high-strength square steel tubular short columns. On the basis of the multi-scale modelling method well verified, a total of 24 multi-scale model were established. The failure mechanism and the influence of different parameters on the size effect of the axial compressive performance were analyzed. The simulation results indicate that high-strength concrete filled high-strength square steel tubular short columns have more obvious size effect than the ordinary-strength concrete filled steel tubular short columns on the axial compressive capacity. Calculation results of equations for axial compressive capacity from Chinese professor Han Linhai, GB 50936-2014 code, AIJ 2008 code and T/CECS 987-2021 specification were compared with the simulation results. The ratio of calculation results of 4 kinds of equations over the simulation results all tend to increase with the increase of member size. Furthermore, 4 size effect coefficient equations were proposed and effectively modified the 4 kinds of equations selected.