Plastic Axial Load and Moment Interaction Curves for Fire-Exposed Steel Sections with Thermal Gradients
Publication: Journal of Structural Engineering
Volume 134, Issue 6
Abstract
Current practice for the design of steel beam-columns (i.e., members under combined axial load and bending) subject to fire is to calculate the capacity of these members assuming a uniform temperature distribution through the depth of the section. This assumption may be acceptable for some members, but there are cases where the member will be heated nonuniformly, thereby developing a thermal gradient through its depth. This paper analyzes the effects of thermal gradients on the combined axial load -moment yield capacity of beam-columns and compares the yield capacity of members with temperature gradients to those with uniform temperature profiles. The prototype beam-columns used in this study are wide-flange (WF) steel sections that are part of a high-rise moment-resisting steel building. This study evaluates the effects of plate thickness, section depth, and the direction of bending (i.e., strong versus weak axis) on the plastic interaction diagram of WF sections with thermal gradients. Results show that a thermal gradient may have a significant effect on the yield capacity of beam-columns, and evaluations that are made assuming a uniform temperature through the section may lead to overestimations or underestimations of the true strength of the section.
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Acknowledgments
Mr. Quiel has been involved with this research project while on appointment as a U.S. Department of Homeland Security (DHS) Fellow under the DHS Scholarship and Fellowship Program, a program administered by the Oak Ridge Institute for Science and Education (ORISE) for DHS through an interagency agreement with the U.S Department of Energy (DOE). ORISE is managed by Oak Ridge Associated Universities under DOE Contract No. DOEDE-AC05-00OR22750. All opinions expressed in this paper are the writers and do not necessarily reflect the policies and views of DHS, DOE, or ORISE.
References
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Copyright
© 2008 ASCE.
History
Received: Sep 5, 2006
Accepted: Nov 1, 2007
Published online: Jun 1, 2008
Published in print: Jun 2008
Notes
Note. Associate Editor: Venkatesh Kumar R. Kodur
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