A 2D beam element for the analysis of flexural buckling of steel structures at elevated temperatures

The paper describes the development of a two-dimensional (2D) nonlinear beam finite element that includes advanced path-following capabilities for detecting bifurcation instability of steel elements subjected to fire loading. A co-rotational formulation was used for describing the beam kinematic. The degradation of the steel mechanical properties at high temperature according to the Eurocode 1993-1-2 was considered by integrating the material constitutive law based on a predetermined temperature field in the cross section. Advanced path-following methods were implemented to analyse the elastic-plastic post-buckling behaviour of compressed steel elements at high temperature without the need of introducing geometrical imperfections. To highlight the practical implications, a parametric analysis showed that the element could reproduce the EN1993-1-2 buckling curve. The obtained outcomes were validated against experimental and numerical data obtained with commercial software ABAQUS and SAFIR.