The transition toward a circular construction economy has increased interest in hybrid structural systems that combine sustainability with performance. Steel-Timber Composite (STC) floors, combining Engineered Wood Products (EWPs) like Cross-Laminated Timber (CLT) with steel, offer a promising solution to reduce embodied carbon while maintaining structural efficiency (Loss et al. 2016; CTBUH 2022). To support reuse and adaptability, demountable shear connections are needed that align with Design for Disassembly (DfD) principles. Most existing STC connections rely on dowel-type fasteners (Loss et al. 2016; Hassanieh et al. 2016, 2017a, 2017b; Ataei et al. 2019; Wang et al. 2020), which offer simplicity and sufficient mechanical performance but are too flexible to enable efficient shear transfer. Recent developments at UHasselt led to the design of a novel demountable connector for STC floors, drawing inspiration from notch-type joints used in timber-concrete composites and pre-assembled metal connectors from timber engineering. This hybrid solution combines high load-bearing capacity and stiffness with rapid installation and disassembly, supporting circular construction principles. However, significant knowledge gaps remain regarding the long-term performance of such connections under indoor service conditions. Moisture-related effects, such as anisotropic swelling, mechano-sorptive creep, and crack formation, are still underexplored, particularly in demountable systems. This study addresses this gap by experimentally assessing the hygroscopic behaviour of STC connections through a humidity cycling test (HCT), providing insights into their durability and reusability in circular construction.
Keywords: Steel-timber composite (STC), humidity cycling test (HCT), Design for Disassembly (DfD)
Authors
Pibbe Willems
Ghent University, Laboratory of Wood Technology (UGent- Woodlab), Department of Environment, Faculty of Bioscience Engineering, Ghent, Belgium
José Gouveia Henriques
CERG, Faculty of Engineering Technology, Hasselt University, Belgium
Alper Turgut
CERG, Faculty of Engineering Technology, Hasselt University, Belgium
Hervé Degée
CERG, Faculty of Engineering Technology, Hasselt University, Belgium
Liselotte De Ligne
Ghent University, Laboratory of Wood Technology (UGent- Woodlab), Department of Environment, Faculty of Bioscience Engineering, Ghent, Belgium
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