Steel beam‐columns subjected to fire

Abstract

AbstractThe flexural and lateral‐torsional buckling resistance of steel beam‐columns subjected to fire is strongly affected by the decreasing stiffness during heating and the non‐linear stress‐strain relationship of steel at elevated temperatures. This paper analyses the spatial buckling behaviour of steel members subjected to combined axial compression and biaxial bending moments with both uniform and non‐uniform bending moment distributions. The results of a parametric study using the finite element approach are presented as temperature‐dependent non‐dimensional M‐N interaction curves and compared to results according to the current European fire design rules as well as a simple calculation model based on the Method1 and 2 approaches currently used for the European ambient temperature design. The comparative study shows that the Method1 and 2 approaches cannot be directly adapted for the fire design of steel beam‐columns in combined axial compression and biaxial bending. The interaction and plasticity factors must be further developed to take advantage of using similar interaction formulae for ambient temperature and fire design.