Structural fire performance of axially and rotationally restrained stainless steel columns

This paper describes a step improvement in the numerical modelling of the structural response of axially and rotationally restrained stainless steel columns at elevated temperatures. The developed finite element models form a sequentially coupled thermal stress analysis that comprises a heat transfer model, a buckling analysis, and a geometrically and materially non-linear stress analysis. The proposed finite element methodology is more sophisticated than any other reported attempts to model the fire response of structural stainless steel that take into account influence of adjoining members. A high degree of predictive accuracy is achieved, with the developed models on average predicting the failure temperatures and times of test specimens reported in the literature within 2% and 6%, respectively. A parametric study is performed that investigates the influence of axial restraint stiffness, rotational restraint stiffness, column slenderness and load level. It is shown that while increasing axial restraint stiffness reduces the failure temperature of stainless steel columns in fire, increasing rotational restraint stiffness has the opposite effect. The methodology and results of this paper will provide both a tool for practice and a suite of results that can be extended to develop the existing and currently limited codified approaches to structural stainless steel design.