Project contact is Cristiano Loss at the University of British Columbia
This research aims at developing novel multi-material deconstructable hybrid connections for mass timber prefabricated buildings. Connections will be conceived in order to (i) meet multi-objective structural performance, (ii) favour modular construction, (iii) favour quick erection of buildings, (iv) quick disassemble and possible reuse of the timber members, and (v) provide seismic-resistant structural assemblies.
Society of Wood Science and Technology International Convention
The application of deconstructable connectors in timber-concrete composite (TCC) floors enables the possibility of disassembly and reuse of timber materials at the end of building’s life. This paper introduces the initial concept of a deconstructable TCC connector comprised of a self-tapping screw embedded in a plug made of rigid polyvinyl chloride and a level adjuster made of silicone rubber. This connection system is versatile and can be applied for prefabrication and in-situ concrete casting of TCC floors in both wet-dry and dry-dry systems. The paper presents the results of preliminary tests on the shear performance of four different configurations of the connector system in T-section glulam-concrete composites. The shear performance is compared to that of a permanent connector made with the same type of self-tapping screw. The failure modes observed are also analyzed to provide technical information for further optimization of the connector in the future.
Project contact is Lech Muszynski at Oregon State University
The aim of this project is to remove this vulnerability by thoughtful conceptualization of basic strategies for optimizing the design of mass timber buildings for successful post-use material recovery/reuse and end-of-life climate benefit. Research questions will include:
1. Is demolition of decommissioned mass timber buildings a viable end-of-life option at all?
2. Can deconstruction be conducted by following construction steps in reverse order?
3.What may be the extent of damage inflicted to the connection nests, connected edges and surfaces of MTP elements during a deconstruction?
4.Can original connection nests be safely reused in structures re-using deconstructed MTP elements?
5.What is the impact of techniques and technologies selected at the design, production, and construction stages on the EOL options and carbon cost of deconstruction,
6. What is the carbon impact of deconstruction on reuse or recycling of MTP elements?
7. Do the existing deconstruction companies in the Pacific northwest have capacity to process mass timber panels that could not be reused?
8. What is the carbon costs of transportation and repurposing/recycling of MTP elements for non-structural uses?
CLT-concrete composite floor systems are a solution for timber buildings with a long-span floor. It yields a reduction of carbon footprint and even eco-friendly structure at the end of its service life. This study will evaluate the structural performance of notched connectors in the CLT-concrete composite floor, comprised of the serviceability stiffness, maximum load, and behavior at failure. The parameters of the test plan are the loaded edge length, the notch depth, the concrete thickness, and the screw length. Other secondary variables are also assessed, such as different loading sequences, speed of test, and timber moisture content. Experimental results prove that the performance of the connector depends significantly but not linearly on the notch depth and the length of the loaded edge. The connector with a deeper notch and a shorter heel will be stiffer and more robust, but it also tends to have a brittle rupture. The test results also help validate a solution for deconstructable connector systems. A nonlinear finite element model of the connector is built and validated versus the experimental results. It yields reasonably good predictions in terms of resistance and can capture the load-slip relationship.