Seismic Performance of Symmetric Unfinished CFS In-Line Wall Systems

Abstract

The current North American standards, AISI S240 (2015) and AISI S400 (2015), provide information that can be used to design cold-formed steel (CFS) framed steel sheet shear walls which meet the seismic demands for a low-rise to mid-rise (3-6 story) buildings. However, experimental data to support code guidelines for taller mid-rise (>6 stories) and high-rise buildings (>10 stories), where large lateral load resistance is required, are lacking. Moreover, most of the experimental research so far has involved testing shear walls under quasi-static monotonic/reversed cyclic loading. In the current research project, shear walls placed in-line with gravity walls were tested at full-scale first under a sequence of increasing amplitude (in-plane) earthquake motions, and subsequently (for select specimens) under slow monotonic pull conditions to failure. Experiments were performed at the NHERI Large High-Performance Outdoor Shake Table at UC San Diego. Selection of wall details was motivated by the design of a CFS archetype building (4 and 10 story) using available experimental data. This paper explains the design details and discusses the experimental response of a baseline wall specimen pair in the test program, which uses compression chord stud packs with a steel tension tie-rods assembly, is unfinished and designed with a symmetric configuration.