Numerical evaluation: AISI S400 steel-sheathed CFS framed shear wall seismic design method

Seismic design provisions for steel-sheathed cold-formed steel framed shear walls, specific to Canada, are not provided in the existing AISI S213 Standard “North American Standard for Cold-Formed Steel Framing – Lateral Design”. A multi-phase approach was adopted in order to develop appropriate seismic design provisions for inclusion in the new AISI S400 Standard “North American Standard for Seismic Design of Cold-Formed Steel Structural Systems”. The approach included the extensive displacement based testing and dynamic testing of shear walls, the analysis of the test data results, the development and calibration of dynamic numerical models in OpenSees, and lastly, the dynamic response history analyses of twelve archetype buildings designed for the seismic hazard in three cities; Halifax (low seismic), Montreal (medium seismic) and Vancouver (high seismic). It is this last phase of the study that is documented herein. Fragility curves were developed from the buildings' response to 44 scaled ground motion records following a method adapted from the FEMA P695 analysis methodology. The results showed that the design method is appropriate, including the seismic force modification factors of Rd=2 and Ro=1.3. Improvement to the predicted seismic response of CFS framed buildings could be forthcoming if one were to account for the contribution of the non-structural gypsum wall panels.