10.26: Parametric numerical analysis of cold‐formed steel Σ‐shaped beams under fire

Abstract

A numerical investigation into the structural behaviour of cold formed steel beams commonly used in warehouses and industrial buildings subjected to fire is presented in this paper. The structural performance of cold-formed steel beams under fire conditions has been studied over the last years. However, the great majority of them have been performed on single and lipped channel beams and assumed that the internal forces and moments at supports of the members remain unchanged throughout the fire exposure. Hence, a detailed parametric numerical investigation into the response of axially and rotationally restrained compound cold-formed steel beams in fire has been addressed in this paper. Therefore, in the first phase of this research, a suitable finite element model was developed and calibrated with results of experimental fire tests previously carried out by the authors. And then, a parametric analysis was undertaken using the calibrated finite element model with the purpouse of investigating numerically the effect of some parameters such as section geometry, initial applied load on the beam, slenderness and the influence of those two ki nds of elastic restraint on the critical temperature of the beams. Finally, the results of this research showed mainly that the critical temperature of this type of beams with elastically restrained thermal elongation may drop significantly and, beyond a certain value of axial or rotational stiffness of the surrounding structure it may be no longer possible to change the fire response of them.