A Parametric Investigation of the Transition Between Beam-Web Shear Buckling and Bottom- Flange Buckling at Elevated Temperatures

In this research, two existing analytical models of beam-web shear buckling and bottom-flange buckling in steel beams at elevated temperatures have been briefly reviewed. Both models are able to track the behaviour from pre-buckling to post-buckling stage, near to the ends of beams. A transition criterion has been proposed to justify which buckling phenomenon occurs in reality, according to the given structural information, such as geometrical dimensions and loading conditions. A number of 3D finite element models have been created using the ABAQUS software. Parametric studies have been carried out to detect the transition from beam-web shear buckling to bottom-flange buckling, as well as an interactive range within which both phenomena occur simultaneously. Comparisons between the analytical and FE models have shown that it is possible to propose criteria to detect the transition between buckling types. The proposed analytical methods provides sufficient accuracy to be developed further, and in due course it will be embodied in global modelling of composite structures in fire as part of a component-based approach to connections and their adjacent zones.