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Structural analysis of multi-story steel frames exposed to travelling fires and tradition design fires

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Title: Structural analysis of multi-story steel frames exposed to travelling fires and tradition design fires
Authors: Rackauskaite, E
Kotsovinos, P
Jeffers, A
Rein, G
Item Type: Journal Article
Abstract: Most of the current understanding of building behaviour in fire is based on the adoption of the standard and parametric temperature-time fire curves. However, these design fires are based on small scale tests and idealize the thermal environment as uniform. Thus, they have important limitations on their applicability to large enclosures. Instead, in large open-plan compartments, travelling fires have been observed. To account for such fires, a design tool called Travelling Fires Methodology (TFM) has been developed and used for design. The aim of the present study is to compare computationally the structural response of a multi-storey steel frame subjected to both uniform design fires (available in current standards) and travelling fires. A two-dimensional 10-storey 5-bay steel frame designed according to ASCE 7-02 is modelled in the general finite element program LS-DYNA. Different fire exposures are investigated. They include travelling fires, Eurocode parametric curves, ISO-834 standard fire and the constant compartment temperature curve from the SFPE standard. These fires are applied to different floors, one at a time, to explore the influence on the structural response, resulting in a total of 80 different scenarios. The development of deflections, axial forces and bending moments is analysed. Uniform fires are found to result in approx. 15–55 kN (3–13%) higher compressive axial forces in beams compared to small travelling fires. However, the results show irregular oscillations in member utilization levels in the range of 2–38% for the smallest travelling fire sizes, which are not observed for any of the uniform fires. Peak beam mid-span deflections are similar for both travelling fires and uniform fires and depend mainly on the fire duration, but the locations in the frame and times when these peak displacements occur are different. The results indicate that travelling fires and uniform fires trigger substantially different structural responses which may be important in the structural design and selection of the critical members.
Issue Date: 26-Jul-2017
Date of Acceptance: 21-Jun-2017
URI: http://hdl.handle.net/10044/1/49614
DOI: https://dx.doi.org/10.1016/j.engstruct.2017.06.055
ISSN: 1873-7323
Publisher: Elsevier
Start Page: 271
End Page: 287
Journal / Book Title: Engineering Structures
Volume: 150
Copyright Statement: © 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC-BY license (http://creativecommons.org/licenses/by/4.0/)
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/K503381/1
Keywords: 0905 Civil Engineering
Civil Engineering
Publication Status: Published
Appears in Collections:Mechanical Engineering
Faculty of Engineering