Innovative lateral load resisting systems for mid-rise timber frame buildings

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Since 2009, various provincial and federal jurisdictions in Canada have amended their respective building codes to increase the storey limit of residential wood frame buildings from 4 to 6 storeys. Increases in height have raised the demand for a stronger shear wall system for construction of mid-rise (up to 6 storey) timber frame buildings that usually require higher resistance against gravity and lateral loads than low-rise (up to 4 storey) buildings. Research related to strong wood frame shear walls is limited. Simply reinforcing the resistance of the traditional shear wall may compromise other structural properties, such as ductility and energy dissipation capacity, which are two of the key characteristics affecting the performance of structures under earthquake loads. In this research program, the main aim is to develop a stronger shear wall system that can be used in construction of mid-rise timber frame buildings that has comparable ductility and energy dissipation capacity to traditional walls. ******In the proposed research, the high lateral resistance of the newly developed wall system will be achieved by re-arranging the three main components used in traditional shear walls: dimension lumber, sheathing panels and nails. Multi-rows of nails will be aligned along the edges of sheathing panels as these nail joints are expected to control the failure mode and lateral resistance of the wall system. Meanwhile, the timber frame will be enhanced by using multiple plates and studs to avoid failure at the frame members. These enhanced plates and studs can also be placed at a 90 rotation with the wider face of dimension lumber nailed to the sheathing panels, which is similar to a midply shear wall system. In this case, multi-shear and multi-row sheathing-to-framing nails are used. A strong hold-down system is required to prevent up-lift failure.******In this research program, the structural performance of the newly developed shear wall system will be investigated through both experimental study and numerical modeling analysis. Two master students in years 1-2 will investigate the performance of connections used in the strong shear walls. At the end of phase 1, the failure mode and mechanical properties of connections with various configurations will be obtained. Two PhD students will continue the research at the system level in phase 2. One of the PhD students will focus on the optimization of design details of shear walls. The other PhD student will focus on the structural performance of timber and timber-based hybrid buildings under seismic load. At the end of this research, it is expected that a better understanding of the structural performance of the newly developed shear wall system will be achieved on three levels: joints, wall systems and the whole building.