An-Najah Staff

For evaluating fire resistance of a reinforced concrete member, temperature profile in the cross section of the member is required. Current simplified approaches and design graphs do not yield reliable temperature predictions in rebar and concrete. In this paper, a simplified approach is proposed for evaluating cross-sectional temperatures in fire-exposed reinforced concrete members. The approach is derived through statistical nonlinear regression analysis, utilizing data generated from finite element analysis. The parameters that were varied in the finite element analysis include sectional geometry, concrete characteristics and fire exposure conditions. The validity of the approach for different types of concrete is established by comparing predictions from the proposed equation with data from fire tests and finite element analysis. Through these comparisons it is shown that the proposed equation gives better predictions of temperatures in reinforced concrete members. The applicability of the proposed approach in design situations is illustrated though a numerical example. The simplicity of the proposed method makes it attractive for use in design situations and for incorporation in design standards.

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.