Seismic performance of multi-storey structures with cold-formed steel wood sheathed shear walls

Despite the widespread use of cold-formed steel (CFS) in Canada, the 2005 National Building Code of Canada (NBCC) do not address the seismic design. Previous research conducted at McGill University resulted in the development of a design procedure and seismic force modification factors related to ductility and overstrength, Rd and Ro, for the CFS frame wood sheathed shear wall system. Based on this prior research, the American Iron and Steel Institute (AISI) included the design procedure and the force modification factors for the wood sheathed shear walls into the North American Lateral Standard for Cold-Formed Steel Framing (AISI S213). In order for this information to be included in the NBCC it was necessary to validate the design procedure, the R values and the 20 m height limit detailed in the AISI S213 by conducting dynamic analyses as well as dynamic tests. Fourteen structures (4, 6 & 7 storeys) were designed and modeled using two different software packages: Ruaumoko and SAPWood. Two different seismic force resisting systems were validated: CFS frame wood sheathed shear walls (Rd = 1.5, Ro = 1.7) and a combination system whereby wood sheathed shear walls and gypsum walls work together (Rd = 1.5, Ro = 1.7). Two seismically active regions in Canada were selected for the design of the structures: Montreal, QC and Vancouver, BC. The performance of the modeled structures was then evaluated based on the ATC-63 methodology developed for the Federal Emergency Management Agency (FEMA) in the United States.;In collaboration with Ecole Polytechnique a shaketable test program was recommended in order to validate/calibrate the behaviour depicted by the dynamic models. As a continuation of the research described in this thesis, full-scale dynamic tests will be performed on several single- and two-storey CFS wood-sheathed shear wall specimens. Predicative dynamic models have been used to estimate the behavior of these proposed dynamic tests.;Given the performance of the models, the shear wall design approach documented in AISI S213 was proven to be satisfactory according to the ATC-63 methodology. The walls provided the necessary shear resistance when subjected to the suite of earthquake records scaled beyond the design level excitation and the structures maintained interstorey drifts far below the recommended 2% limit under design level earthquakes. The seven storey structures proved that buildings designed with storey heights exceeding the 20 m limit still perform adequately; however the constructability becomes limited as the number of storeys increases. In addition, the gypsum used as a finishing was found to significantly reduce the interstorey drift under dynamic loads. Structures designed with wood sheathed shear walls and gypsum as part of the SFRS show even greater improvement however necessitate a greater number of shear walls in response to the lower ductility expected and the reduced Rd value used in design.