Probabilistic design of timber joints

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Forest industries are key drivers of the Canadian economy, but adversities like the Mountain Pine Beetle epidemic (which causes an oversupply of timber) and the downturn of the US housing market (which significantly reduced timber exports) are challenging the sector. As a consequence, innovative solutions are required to expand the use of timber beyond traditional light-frame based residential construction. The non-residential construction sector represents a substantial market for structural materials, yet it is relatively untapped by timber, partly because of a lack of appropriate design tools. The proposed research will fill that gap by developing novel design tools for timber joints. Joints play a crucial role in the design of timber structures. Practitioners have at their disposal a series of methods to connect load bearing elements: mechanical fasteners, load transmission through direct contact, and adhesive bonding. All of these methods result in geometries that generate complex multi-axial stress singularities for which traditional deterministic design cannot be applied in a safe and efficient manner. The long-term goal of the research is to develop reliable, robust and implementable tools to design a wide range of joints, both between two timber members, and also between timber and other materials. The tools will be based on a probabilistic mechanical description of all materials applied and the involved degradation and failure mechanisms. The research builds on a probabilistic design method for timber joints under static short term loading that I have developed previously, implemented into a practical design routine, and benchmarked by a direct comparison with tests on carpentry and adhesively bonded joints. Within the next five years, my team will develop probabilistic design tools for timber joints involving metal fasteners and for other relevant loading conditions. Ultimately, the successful implementation of the research programme will have a decisive impact on the structural use of timber, and increase its market share in a variety of applications.