A simplified approach for predicting temperatures in fire exposed steel members

For evaluating fire resistance of steel structural members, temperatures in the cross section of the member are required. In this paper, a simplified approach for evaluating cross sectional temperature in contour protected steel members exposed to fire is presented. The approach is derived utilizing simplifying assumptions to the general heat transfer equation for standard fire and is then extended for application under design fire scenarios. The proposed approach is applicable for both protected and unprotected steel sections. The validity of the approach is established by comparing predicted temperatures with those obtained from finite element analysis generated via ANSYS. In addition, predictions from the proposed method are also compared with the temperatures predicted by best-fit method. The comparisons to test data, finite element results and best-fit method indicate that the proposed simplified method gives good predictions of fire induced thermal gradient and temperature history in steel sections under any fire exposure. The simplicity of the proposed method makes it attractive for use in design situations.