Thermal Gradient Estimation due to Surface Heat Exchange in Steel I-Sections
Publication: Journal of Structural Engineering
Volume 143, Issue 9
Abstract
Fire poses a great threat to steel structures. An accurate estimation of the temperatures in structural member cross sections is the first and most crucial step to calculate fire-induced forces and moments and ultimately to evaluate the fire performance of a structural system. This study focuses on the thermal behavior of perimeter I-section columns in steel buildings subjected to the standard fire curve. Because I-sections have a concave enclosure or cavity, the surfaces in the enclosure exchange heat by radiation, which significantly changes the thermal gradient in the section. An efficient algorithm is developed to calculate the radiation heat flux generated by surface heat exchange in I-section enclosures. The results show that the surface heat exchange in the enclosure reduces the thermal gradient as much as 40% for shorter and wider sections. The fire test results confirm the numerical findings. Using a simplified equation of a partially restrained column, it is shown that the thermally induced moment reaches as much 60% of the column plastic moment capacity, which indicates a significant reduction in the load-bearing capacity of the building structure.
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Acknowledgments
The author acknowledges the Marie Curie International Incoming Fellowship (FP7-PEOPLE-2012-IIF) “Fire Resistance of Connections in a Composite Floor System”: CONFIRE 328993, Bogazici University Scientific Research Project BAP: 7122P, and 3001-TUBITAK Project: 114M791, which provided the funding for this study. The author is grateful for the assistance of Baturay Ozgurun for the development of the FEHEAT finite element code graphical user interface, which facilitated the parametric study.
References
Abaqus [Computer software]. Dassault Systèmes Simulia, Providence, RI.
AISC. (2005). Steel construction manual, Chicago.
CEN (European Committee for Standardization). (2002). “Actions on structures. 1–2: General actions—Actions on structures exposed to fire.” Eurocode 1, EN 1991-1-2, Brussels, Belgium.
CEN (European Committee for Standardization). (2005). “Design of steel structures. 1–2: General rules—Structural fire design.” Eurocode 3, EN 1993-1-2, Brussels, Belgium.
Emery, A. F., Johansson, O., Lobo, M., and Abrous, A. (1991). “A comparative study of methods for computing the diffuse radiation view factors for complex structures.” Int. J. Heat Mass Transfer., 113(2), 413–422.
Exova. (2016). “Warrington certifire certification: Vermiculux board TS14 board/spray protection for steelwork.”⟨https://www.warringtoncertification.com/certificates/CF421/1816/CF421_Promat%20UK.pdf⟩ (Jul. 11, 2016).
Fu, H. C., Ng, S. F., and Cheung, M. S. (1990). “Thermal behavior of composite bridges.” J. Struct. Eng., 3302–3323.
Ghojel, J. I., and Wong, M. B. (2005). “Heat transfer model for unprotected steel members in a standard compartment fire with participating medium.” J. Construct. Steel Res., 61(6), 825–833.
Huebner, K. H., Dewhirst, D. L., Smith, D. E., and Byrom, T. G. (2008). The finite element method for engineers, Wiley, New York.
ISO. (1999). “Fire-resistance tests—Elements of building construction—Part 1: General requirements.” ISO 834-1, Geneva.
MATLAB [Computer software]. MathWorks, Natick, MA.
Rao, V. R., and Sastri, V. M. K. (1996). “Efficient evaluation of diffuse view factors for radiation.” Int. J. Heat Mass Transfer, 39(6), 1281–1286.
Selamet, S. (2011). “Behavior, design and finite element modeling of shear connections under fire hazard.” Ph.D. thesis, Princeton Univ., Princeton, NJ.
Selamet, S., and Garlock, M. (2013). “Plate buckling strength of steel wide-flange sections at elevated temperatures.” J. Struct. Eng., 1853–1865.
Selamet, S., and Garlock, M. (2014). “Fire resistance of steel shear connections.” Fire Saf. J., 68, 52–60.
SFPE (Society of Fire Protection Engineers). (2002). SFPE handbook of fire protection engineering, 3rd Ed., Gaithersburg, MD.
Shapiro, A. B. (1985). “Computer implementation, accuracy, and timing of radiation view factor algorithms.” Int. J. Heat Mass Transfer, 107(3), 730–732.
Siegel, R., and Howell, J. R. (2002). Thermal radiation heat transfer, 4th Ed., Taylor & Francis, New York, 155–192.
Sparrow, E. M., and Chess, R. D. (1978). Radiation heat transfer, Augmented Ed., Hemisphere Publishing Corporation, Washington, DC, 81–144, 339–349.
Tan, K. H., and Huang, Z. F. (2005). “Structural responses of axially restrained steel beams with semirigid moment connection in fire.” J. Struct. Eng., 541–551.
TSI (Turkish Standards Institute). (2016). “I-section temperature development with ISO curve.”, Construction Materials, Fire and Acoustics Laboratory, Istanbul, Turkey.
Usmani, A. S., Rotter, J. M., Lamont, S., Sanad, A. M., and Gillie, M. (2001). “Fundamental principles of structural behaviour under thermal effects.” Fire Saf. J., 36(8), 721–744.
Vácha, J., Kyzlík, P., Both, I., and Wald, F. (2016). “Beams with corrugated web at elevated temperature, experimental results.” Thin Walled Struct., 98, 19–28.
Virdi, K. S., and Wickstrom, U. (2013). “Influence of shadow effect on the strength of steel beams exposed to fire.” 20th Int. Conf. on Computer Methods in Mechanics, Poznan Univ. of Technology, Poznan, Poland.
Walz, J, Choe, L, Surovek, A, and Varma, A. (2014). “Section characterization of wide-flange steel sections subjected to combined thermal and mechanical loading.” J. Struct. Eng., 04014162.
Wickstrom, U. (2001). “Calculation of heat transfer to structures exposed to fire—Shadow effects.” Proc., 9th Int. Conf., Interscience Communication Ltd., Edinburgh, Scotland, 451–458.
Wickstrom, U. (2004). “Heat transfer by radiation and convection in fire testing.” Fire Mater., 28(5), 411–415.
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Published In
Journal of Structural Engineering
Volume 143 • Issue 9 • September 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Jul 26, 2016
Accepted: Feb 22, 2017
Published online: May 29, 2017
Published in print: Sep 1, 2017
Discussion open until: Oct 29, 2017
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