Advancing lateral design standards for cold-formed steel structures in Canada

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The proposed research is directed towards improving the state of knowledge and design provisions in Canada of cold-formed steel (CFS) lateral load resisting structures. The Canadian Sheet Steel Building Institute has expressed the need for two related research projects: 1) to develop information to aid in the design and analysis of CFS framed floor and roof diaphragms, and 2) to develop CFS shear walls, sheathed with steel, with nominal resistances that are adequate for use in mid-rise construction (up to 5 storeys). The 1st project addresses the situation that engineers face where they must make gross simplifications in the building analyses for the diaphragms of CFS framed buildings. Simplifications that lead to inefficiencies, as the energy dissipating potential of the diaphragm & diaphragm-to-wall interface is ignored; inaccuracies as the forces transmitted by the diaphragm to the walls are approximated, and the forces that develop in the diaphragms themselves are not well understood; these lead to an incomplete understanding of the full 3D lateral force resisting system. Research on model development is underway; however, there is immediate need for test data on diaphragms to improve model accuracy and facilitate an improved understanding of diaphragm response. The objective of this project is to provide characterization of typical CFS floor & roof diaphragm response by means of laboratory testing, including full load vs. deformation hysteretic response. The 2nd project involves all-steel shear wall configurations (non-combustible) that can carry lateral loads in excess of 30 kN/m to bridge the gap between CFS and hot-rolled steel lateral framing shear wall systems, and to expand on the existing range of shear strength values currently listed in relevant design standards, e.g. AISI S400. The general objectives of the proposed research are: (i) determine shear resistance values for CFS frame steel sheathed shear walls constructed of thicker framing and sheathing members than currently available for design through an improved strip analysis method and testing approaches; (ii) determine the effect of frame blocking for low and high aspect ratio walls; and (iii); recommend nominal shear resistance values for Canada.