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Thermal response and capacity of beam end shear connections during a large compartment fire experiment

Published

Author(s)

Xu Dai, Lisa Y. Choe, Erica Fischer, Charles Clifton

Abstract

To perform structural fire design and analysis for steel-framed composite structures, the role of steel connections is essential. However, the current design provisions are based on small-scale fire experiments, and their reliability is questionable for determining temperatures in connections within full-scale structures under large compartment fires, especially when the structural elements are under fire protection. Partly to address this issue, a large compartment fire test was conducted in a two-story steel framed building, which has a composite floor system applied by a design mechanical load 2.3 kPa. The test compartment involved ten beam end shear connections, under a fire loading following a standard fire curve up to 107 mins. Then the fire was extinguished and mechanical loading was removed. The Eurocode 3 provision was investigated through comparing the experimental measurements on the connection components, with the prediction based upon the connected beam bottom flange temperature at midspan, and the section factor method. This shows that the Eurocode 3 provisions are conservative on both the maximum temperature prediction and the cooling rate. Nevertheless, it is worth noting in this test the fire protection at the connection region was at least 43% thicker than the protection on the beams. Furthermore, during the post-fire inspection, it was still found one connection experienced bolts shear failure. It suggests that solely designing connections through temperature provisions will not guarantee a safe structural fire design; the axial load demand of the connection due to restraints to thermal elongation or contraction must also be taken into account in future design guidance.
Proceedings Title
SiF20 - The 11th International Conference on Structures in Fire
Conference Dates
November 30-December 2, 2020
Conference Location
Brisbane

Keywords

Connections, fire test, Eurocodes, temperatures, capacity, shear tab

Citation

Dai, X. , Choe, L. , Fischer, E. and Clifton, C. (2020), Thermal response and capacity of beam end shear connections during a large compartment fire experiment, SiF20 - The 11th International Conference on Structures in Fire, Brisbane, -1, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931028 (Accessed June 24, 2024)

Issues

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Created November 29, 2020, Updated December 22, 2020