Cyclic testing of two- and three-story CFS shear-walls with reinforced end studs

Abstract

Cyclic loading tests on seven cold-formed steel shear walls were performed concerning the influence of the end stud type, stud section, interlayer action and openings. The results showed that: (1) failure modes similar to the single-story shear wall test results mainly occurred in the underlying wall; (2) two-story specimens with an aspect ratio of less than 2.0 had shear type failures, whereas the failure mechanism of three-story specimens with an aspect ratio larger than 3.0 tended to be bending failure; (3) both shear strength and non-deformability were notably enhanced by adopting reinforced end studs, and the specimens exhibited better energy-dissipating capacity after their yield limit; (4) when the web depth of end columns was enlarged from 89mm to 140mm, for a fully sheathed specimen, the elastic stiffness of the lower story was improved by nearly 41.5%, while there was no meaningful reduction in the non-deformability of the upper story if the opening area ratio was 20.8% at most; (5) due to the second story, the base shear of the two-story specimen was less than the shear capacity of the corresponding single-story shear wall; and (6) the decreased percentages of the shear strength for specimens with similar opening area ratios were nearly the same, which is irrelevant to the stud section. Based on a bearing mechanism analysis of the perforated shear wall, a simplified method was proposed to predict the base shear for a mid-rise shear wall with a relative error of 1.5% between the calculated and test results.