Calculation method for the residual stability bearing capacity under axial compression of steel tube members exposed to a high temperature

Fire accidents occur occasionally when grid structures are extensively applied, although many grid structures do not suffer general failure after fire disasters and can be used again after reasonable evaluation and reinforcement. To reasonably evaluate the residual load bearing capacity of grid structures, this paper investigated stability bearing capacity of steel tube members in grid structures after fire disasters through axial compression experiment and numerical simulation. Axial compression experiments performed on 32 steel tubes after exposure to the ISO-834 standard fire, and three highest fire temperatures were considered, including 600 °C，800 °C and 1000 °C. The temperature distributions in the specimens during the heating and related mechanical properties such as load-displacement curves, ultimate loads and strain distributions of the specimens, were obtained and analyzed. Finite element analysis was also conducted by using ABAQUS software. Then, the main factors influencing the residual stability bearing capacities of the steel tube members exposed to high temperatures were obtained through a lot of numerical analysis. Based on the results of experiments and numerical analysis, the formula for the computation of the residual stability bearing capacities of the steel tube members after fire disasters was presented. And calculated results using the formulas accorded well with experimental results.