High performance timber connections with steel perforated plate as structural fuse

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Tall wood buildings are now technically feasible as a result of advancements made in the development of modern engineered wood products. One of the major concerns for tall wood buildings is their capacity to perform safely under seismic motions. Desirable performance attribute under seismic action is the ability of a structure to undergo large deformation, as a means to dissipate seismic energy, without collapse. For wood structures, this ability can only be accomplished if the connections in the structures contain metal components that act as a source of energy dissipation. An approach of using the so-called structural fuse to dissipate energy will be explored in this research program. This approach has been applied in steel structures, but application in wood structures will require further research. The proposed program expands on current research by the applicant to further develop a connection system that consists of a perforated steel plate connecting two or more timber members. The part connecting the steel plate to a timber member will be detailed with metal fasteners, and designed to be stronger than the perforated steel plate to ensure that the target energy dissipation would occur in the steel plate under seismic actions. The perforation pattern consists of a number of circular holes spaced at regular distance. This pattern would facilitate tuning of the perforated plate to achieve the desirable mechanical properties, such as strength, stiffness, ultimate displacement and energy dissipating capacity, and therefore the development of design specifications. As the term fuse implies, another advantage of this type of connection is that the damaged plate can be replaced with relative ease after a strong seismic event. The proposed research will be undertaken by two MSc and two PhD students. The first PhD student will investigate the influence of geometry arrangement and dimensions of perforation pattern and plate material properties on connection attributes. The first MSc project will investigate the influence of bi-directional loading on critical design properties of perforated plate. The second MSc project will study the over-strength factor that needs to be applied to the part of the connection that connects the perforated steel plate to the timber member. This part shall be over-designed to prevent fracture in wood material, but there is currently no reliable guidance on suitable over-design factor to be used. The second PhD thesis project will study the performance of the mass timber structural systems, such as shear walls, that incorporate the developed perforated plate connection. This project was motivated by discussion with design engineers who have identified the need to have economical and reliable connection systems for tall wood buildings. The success of the proposed project will allow mass timber to be considered as a viable, low carbon footprint structural material for structures, especially in seismic-active regions.