Fire performance of hybrid mass timber beam-end connections with perpendicular-to-wood grain reinforcement
Journal of Structural Fire Engineering
Article publication date: 5 January 2022
Issue publication date: 22 September 2022
The fire resistance of timber structures is heavily dependent on the fire behaviour of the connections between its structural elements. The experimental study presented in this paper aimed to investigate the fire performance of glued-laminated timber beam connections reinforced perpendicular-to-wood grain with self-tapping screws (STS).
Two full-size fire experiments were conducted on glulam beam-end connections loaded in flexure bending. Two connection configurations, each utilizing four steel bolts arranged in two different patterns, were reinforced perpendicular to wood grain using STS. The bolt heads and nuts and the steel plate top and bottom edges were fire protected using wood plugs and strips, respectively. Each connection configuration was loaded to 100% of the ultimate design load of the weakest unreinforced configuration. The test assemblies were exposed to elevated temperatures that followed the CAN/ULC-S101 standard fire time–temperature curve.
The experimental results show that the influence of the STS was significant as it prevented the occurrence of wood splitting and row shear-out and as a result, increased the fire resistance time of the connections. The time to failure of both connection configurations exceeded the minimum fire resistance rating specified as 45 min for combustible construction in applicable building codes.
The experimental data show the effectiveness of a simple fire protection system (i.e. wood plugs and strips) along with the utilization of STS on the rotational behaviour, charring rate, fire resistance time and failure mode of the proposed hybrid mass timber beam-end connection configurations.
The research study presented in this paper has been supported in part by the NSERC Discovery grants awarded to the second and third authors. The authors of this paper would like to thank lab technologist Cory Hubbard for his great assistance in the Civil Engineering’s Structures Laboratory at Lakehead University.
Okunrounmu, O., Salem, O.(S). and Hadjisophocleous, G. (2022), "Fire performance of hybrid mass timber beam-end connections with perpendicular-to-wood grain reinforcement", Journal of Structural Fire Engineering, Vol. 13 No. 4, pp. 433-450. https://doi.org/10.1108/JSFE-06-2021-0036
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