GMNIA with beam elements and strain limits based fire design approach for steel beams and beam–columns

Abstract

The use of advanced analysis techniques harnessing the capabilities of the currently available computational resources can lead to considerably more accurate fire design of steel structures relative to the currently adopted simple fire design methods in practice. In this paper, a structural steel fire design method by Geometrically and Materially Nonlinear Analysis with Imperfections (GMNIA) and using strain limits is put forward for the fire design of steel beams and beam–columns. In the proposed fire design method, the GMNIA of a steel member or structure is performed using computationally efficient beam finite elements and strain limits are adopted to account for the detrimental effects of local buckling on the ultimate capacities. To verify the accuracy of the proposed method, extensive numerical parametric studies are conducted through shell finite element modelling. The results indicate that the proposed approach provides accurate and safe ultimate resistance and limit temperature estimations for steel beams and beam–columns in fire, with a considerably higher level of accuracy and reliability relative to the provisions of the European structural steel fire design standard EN 1993-1-2.