FEMA P695 seismic performance evaluation of Cold-formed steel buildings with different shear wall strengths and stiffnesses

Lateral load capacity and stiffness of CFS framed OSB sheathed shear walls can be improved by increasing the number of fasteners between sheathing panel and framing members or by providing sheathing on both sides of panel. Both of these methods could be a viable option to meet high seismic demands when the number of walls is limited by architectural or other concerns. With the increasing use of CFS building systems in high seismic regions, such applications are expected to be more widespread in the future. The present study aims to investigate the seismic response of CFS framed archetype buildings utilizing OSB sheathed wall panels with different levels of stiffness and shear resistance. Nonlinear time history analyses were conducted on 28 archetype buildings and collapse performance evaluation was performed according to FEMA P695 methodology. Load-displacement hysteresis behaviors of wall panels measured in a recent experimental study were adopted to simulate the shear wall response in the numerical models. Buildings utilizing shear walls that are sheathed with OSB panels on one side with 300 mm fastener spacing possess limited overstrength and fail to satisfy the performance criteria regardless of the response modification coefficient used for design. With the use of shear walls that are constructed with 50 mm fastener spacing and single or double sided sheathing configurations, the building design is governed by drift limitation instead of strength requirement. Irregular drift profiles occur with lateral displacements localizing at the first floor when shear walls with single sided sheathing and loose fastener layout is utilized. Using shear walls with a dense fastener layout results in a uniform distribution of lateral displacements among floors.