Behavior of Unrestrained and Restrained Steel Columns Adjacent to Localized Fire

Published

December 12, 2014

Author(s)

Chao Zhang, John L. Gross, Therese P. McAllister, Guo-Qiang Li

Abstract

Steel columns may be exposed to thermal radiation from localized burning of a fire source nearby. Current structural fire design methods are based on uniform heating and, therefore, uniform temperature conditions, and no practicable methods are provided to calculate the thermal radiation from a localized fire and the temperature of exposed steel columns. This paper is one of two independent papers on the behavior of steel columns subjected to localized fire. In this paper, the buckling behavior of steel columns adjacent to a fire source was investigated. A simple approach was proposed to calculate the temperature of steel columns adjacent to localized fire. Coupled thermal-mechanical simulations were conducted. Both unrestrained, axially restrained, and rotationally restrained steel columns of various load ratios and dimensions subjected to different heating conditions were considered. The study finds that the temperature distribution within steel columns adjacent to localized fire is highly non-uniform both transversely and longitudinally, and is asymmetrical in the steel cross section. Due to asymmetrical non-uniform temperature distributions, buckling temperatures of both unrestrained and axially restrained steel columns adjacent to localized fire may be much lower than those of columns subjected to both the standard ISO834 fire and uniform steel temperature condition. The location of localized fire relative to the column has significant effect on the behavior of both unrestrained and restrained steel columns. Structural fire design for steel columns based on the standard ISO834 fire or uniform steel temperatures may not be conservative if the potential real fires are localized fires that are adjacent to the columns.

Citation

Journal of Structural Engineering-ASCE

Pub Type

Journals

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DOI Link

Keywords

Steel columns, Localized fire, Buckling, Non-uniform temperature distribution, axial and rotational restraints, Couple thermal-mechanical simulation

Citation

Zhang, C. , Gross, J. , McAllister, T. and Li, G. (2014), Behavior of Unrestrained and Restrained Steel Columns Adjacent to Localized Fire, Journal of Structural Engineering-ASCE, [online], https://doi.org/10.1061/(ASCE)ST.1943-541X.0001225 (Accessed April 23, 2024)