Shear–bending interaction in steel plate girders subjected to elevated temperatures

• Steel plate girders with rigid and non-rigid end posts at elevated temperatures considering shear - bending interaction.
• Parametric numerical study at both normal and elevated temperature.
• Comparisons with the EC3 prescriptions for shear buckling and shear–bending interaction safety verifications.

The purpose of the current study is to analyse the behaviour of steel plate girders with rigid and non-rigid end posts subjected to elevated temperatures, with the aim of assessing the interaction between shear and bending in case of fire. The intentional low stiffness of the flanges may precipitate the failure of these plate girders, making the interaction between shear and bending an important phenomenon which is also analysed in this work. A parametric numerical study was performed involving a wide range of cross-section's dimensions, plate girders’ aspect ratios and steel grades. Plate girders were numerically tested at both normal and elevated temperature, considering three different uniform temperatures 350 °C, 500 °C and 600 °C. The influence of the geometrical imperfections, as well as the residual stresses, was taken into account. Finally, the numerical results were compared to the EC3 prescriptions for shear buckling and shear–bending interaction safety verifications, adapted to fire situation by the direct application of the reduction factors for the stress-strain relationship of steel at elevated temperatures.