Prediction of Buckling Strength of Steel Column at Elevated Temperatures Based on Shanley Column Concept

Design curves for steel columns at elevated temperatures in Eurocode 3 and AISC 360 become less accurate for temperatures below 400°C, whereas these low temperatures could be significant if the columns are subjected to high axial load. This study proposes an improved buckling formula covering a wide range of temperatures between 20°C and 800°C. To this end, it is first shown that the Shanley column model can accurately capture the continuous variation in temperature-dependent buckling strength. It is also shown that the buckling curve formula derived based on the Shanley model can be formulated in a functional form similar to the design equation in Eurocode 3. A less sophisticated stress-strain relationship is first derived for use in the Shanley model, and a new buckling curve is proposed therefrom. The proposed buckling curve is validated against numerical analysis results for nondimensional slenderness ratios from 0.2 to 2.0 and temperatures from 20°C to 800°C. A comparison with available experimental data is made to further demonstrate the improved accuracy of the proposed formula compared to Eurocode 3 and AISC 360.