Zidi Yan

The building and construction (B&C) industry remains one of the highest greenhouse gas emitting and resource intensive sectors globally. Despite the recent trend to use renewable carbon sequestering building materials, such as timber, a paradigm shift is needed to transition the B&C industry towards an ‘absolute zero’ circular economy. Design for adaptability (DfA) allows buildings and their components to remain in use for longer by responding to changing environmental conditions and occupant needs. This paper provides a review of design principles to enable adaptability for timber buildings through design for disassembly (DfD) and reuse, as well as a systematic review of reversible timber connection systems that enable DfA and DfD.

Fastener products are commonly exported to different continents, and it is important to understand their performance in local timber species and construction practices. This paper investigates the effects of cyclic moisture changes on the withdrawal performance of yellow-zinc and nickel-zinc coated European screws in Australian copper chrome arsenate (CCA) treated Southern Pine, up to a maximum of 24 cycles. A 68–78% loss of the initial withdrawal strength was observed after three cycles, but this was recovered after twelve cycles. Overall, screws lost at least 50% of their initial strength after 24 cycles, regardless of the treatment or fastener coating. The corrosion resistance of nickel-zinc screws in CCA-treated timber was superior to that of yellow-zinc screws in the first three cycles, but the difference disappeared as the moisture cycle number increased. In CCA-treated timber, the corrosion rates of yellow-zinc screws were 40% higher than those in untreated timber. Although nickel-zinc screws were relatively more corrosion-resistant than yellow-zinc screws, the strength loss caused by corrosion confirms that the selected screws are best suited for indoor use. Finally, following a comparative analysis of test results, some recommendations were made in this paper for future research.

This paper provides a novel insight into using reversible mass timber connectors in light-timber framed (LTF) construction to create dismountable, panelised LTF construction systems that enable adaptable building design and panel reuse in the context of a circular economy. The study presented in this paper focused on Australian LTF panelised construction:. A total of 10 IdeFix 304 connectors by SIHGA GmbH, and 20 M20 connectors by SHERPA Connection Systems GmbH were installed in Australian machine graded pine and subjected to monotonic tensile and shear loads to assess their feasibility in the given application. Two strength prediction models were evaluated in comparison to experimental results: Formulae given in the manufacturers’ European Technical Assessments (ETAs) and a prediction model adapted from literature. On average, the latter was more accurate in the given configuration. Considering the set goal of repeated assembly and disassembly, the connectors with a tight fit faced tolerance issues due to moisture fluctuations. Furthermore, rupture of the connector was observed in some instances, owed to higher screw withdrawal capacity in Australian timber. A reduction of the number of screws or their length is suggested to achieve a more ductile response with screw withdrawal. Finally, following comparative analysis of experimental tests and prediction models, recommendations were made for future design of novel LTF panel connectors in the context of disassembly and reuse.