Elevated temperature evaluation of an existing steel web shear buckling analytical model

Steel plate girders with slender webs are particularly susceptible to severe damage when subjected to high temperatures due to fire. Using nonlinear finite element (FE) models, this study examines the buckling strength of steel plate girder webs subject to fire temperatures. The models were validated with experimental results presented by other researchers, and the validation study resulted in recommendations for appropriate FE representations of material properties and boundary conditions. The elastic shear buckling stress (τ_cr) and ultimate shear buckling stress (τ_u) was then studied for web plates with various span-to-depth (a/D) ratios and a range of temperatures representing fire conditions. The results of this parametric study were compared to predictions given by the Basler-Thürlimann (BT) closed-form solution, which was originally developed to predict τ_u at ambient temperature. Various representations of the elevated temperature stress, at the time of τ_u, were used in the BT solution and compared to the FE results. It was found that the BT solution provides adequate predictions of τ_u at elevated temperatures with appropriate substitutions for the yield stress.