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Owolabi, David Oladotun

University of British Columbia

The growing interest in mass timber construction is spurring research into new connections, lateral load-resistance systems, seismic and fire safety design. In the flooring segment, cross-laminated timber (CLT) and CLT-concrete composite floor systems are seeing increased application, while other timber-based composites such as timber-steel and timber-timber composites are not as explored. Studies on the vibration serviceability of mass timber-based floor systems have also received little attention, despite being a crucial governing design consideration. Against this backdrop, this research investigated the vibration characteristics and serviceability performance of a modular prefabricated timber-based floor system comprising cold-formed steel beams fastened to CLT panels. CLT enables two-way load bearing, while steel possesses superior strength-to-weight ratio and reuse potential compared to concrete. Its ductility also compensates for the brittle tensile failure of timber. The research entailed vibration experiments, subjective vibration performance evaluations and numerical simulations with random walk models, considering various parametric configurations: CLT grade, beam spacing, shear connection spacing, boundary condition, and module combination. The efficacy of sand as a passive damping mechanism in the floor system was also investigated. The experimental results revealed that the floor is a high-frequency system with transient vibration response, low static deflection, and vibration modes mainly controlled by the spacing of its beams. Against the common assumption that simply-supported floors perform worse than those with fixed supports, the numerical analysis highlighted the dependence of the response of the floor system, and hence its performance, on both boundary condition and observer location. Near supports, the simply-supported floor had inferior performance metrics compared to its fixed support variant, while at the mid-span, the latter registered poorer metrics. The results also indicated that a more deformable floor with better energy dissipation could outperform a stiffer one in vibration serviceability, underscoring the critical role of damping in achieving favourable performance. The efficacy of loose sand in attenuating vibration through inter-particle frictional interaction and added mass was verified, with up to 7 % damping attained in floors with loose sand-infill – an additional 2 % damping than those without sand on average. As this is a maturing field, recommendations for future studies were offered.

Text

2025-05-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90964

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/