Cold-Formed Steel Shear Walls in Ledger-Framed Buildings

The objective of this paper is to detail recent cyclic testing on Oriented Strand Board (OSB) sheathed cold-formed steel (CFS) shear walls. The shear walls are designed for a two-story ledger-framed building that will undergo full-scale shake table testing as part of the National Science Foundation funded Network for Earthquake Engineering Simulation (NEES) project: CFS-NEES (www.ce.jhu.edu/bschafer/cfsnees). While the overall goal of the project is to enable performance-based seismic design for cold-formed steel framed buildings, the specific goal of this work is to determine how practical building details impact the stability, stiffness, strength, and ductility of cold-formed steel shear walls. Monotonic and cyclic (CUREE protocol) tests are conducted on 4’×9’ (1.22m×2.74 m) and 8’×9’ (2.44m×2.74 m) shear walls utilizing back-to-back chord studs and OSB sheathing on the exterior. Practical building details studied include the impact of (a) ledger track, which is attached to the top of the interior face of the wall, (b) gypsum, which is attached to the interior face of the wall below the ledger track, (c) locations of panel seams, both horizontal and vertical in the OSB, and (d) the impact of differing stud dimensions for the field studs. In each case the impact on stability (particularly of the chord studs), stiffness (both initial and degraded), strength, and ductility are assessed. The information will be used to assess current design procedures utilizing AISI-S213-07 and to develop improved nonlinear models of the CFS-NEES model building so that full building system performance can be assessed.

View content