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Fire Resistance of Unprotected Ultra Shallow Floor Beams (USFB): A Numerical Investigation

Maraveas, C., Tsavdaridis, K. D. ORCID: 0000-0001-8349-3979 & Nadjai, A. (2017). Fire Resistance of Unprotected Ultra Shallow Floor Beams (USFB): A Numerical Investigation. Fire Technology, 53(2), pp. 609-627. doi: 10.1007/s10694-016-0583-5


This paper presents the fire resistance behaviour of partially encased in concrete ultra shallow floor beams (USFB) using numerical analysis method based on material specifications of the EN1994-1-2. Investigating the behaviour of USFBs under elevated temperatures is crucial in determining their fire resistance and evaluating their overall performance in contemporary construction. Even though the manufacturing company provides fire resistances for USFBs based on EC4-1-2 procedures, their response to elevated temperature effects remains up to date neither well documented nor clearly understood. The analyses involved two different beams of span 5 m and 8 m respectively, as specified by the manufacturer. Analysis results showed that such beams, when unprotected, experience severe temperature gradients if exposed to fire, as the lower flange still remains unprotected in contrast to the concrete encased part of the cross-section. As it was anticipated, the moment capacity governs the fire resistance of the beams and the load factor highly effects the elevated temperature behaviour. In addition, the loss of the lower flange, which develops high temperatures, is not compensated by the web and consequently the moment capacity ultimately depends on the temperature of the lower flange. Results also suggest that simulated beams sustained the applied load for approximately 40 min of exposure to the standard fire.

Publication Type: Article
Additional Information: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Publisher Keywords: Ultra Shallow Floor Beams; Fire Resistance; Composite; Flooring Systems; Moment Capacity; Shear Capacity
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TH Building construction
Departments: School of Science & Technology > Engineering
SWORD Depositor:
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Available under License Creative Commons: Attribution International Public License 4.0.

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[thumbnail of USFB_R4_final.pdf] Text - Accepted Version
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