Architecturally Exposed Structural Steel

Local buckling is a failure mode commonly observed in thin-walled structural steel elements. Even though its effect on their behaviour at ambient temperature conditions is well documented and incorporated in current design codes, this is not the case when such elements are exposed to fire. This paper focuses on the occurrence of local buckling in steel members at elevated temperatures by conducting a thorough review of the literature. Experimental data (over 400 in total) gathered from 16 different sources are presented for both hot-formed as well as cold-formed elements made from different cross-sectional geometries (rolled or welded H-sections, box sections, channels etc). The effect of local buckling (and the various parameters that influence it) on the failure temperature is discussed based on the collected experimental evidence. Finally, the methods (numerical modelling and proposed analytical expressions) used by different authors to understand this phenomenon for steel members exposed to fire are discussed.

Cast iron columns were used in many 19th century structures. Many such structures are still in use today and it is important that they fulfill the current requirements on fire resistance. This paper presents the results of a comprehensive study of the behavior and fire resistance of cast iron columns based on extensive numerical simulations using ABAQUS. The ABAQUS simulation model was validated against six fire tests performed in the USA in 1917. The validated model was then used to investigate the effects of several parameters (column slenderness, load factor, load eccentricity, imperfections of column and cross section, axial restraint) on the behaviour of cast iron columns in fire. The parametric study results indicate that the fire resistance is governed by the applied load and these columns are sensitive to load eccentricity. Based on a comparison between the numerical simulation results and predictions of the EN 1993-1-2 method which is for modern steel structures, it has been found that the EN 1993-1-2 method can give safe and reasonably accurate estimate of the strength and fire resistance of cast iron columns.