Distortional Buckling of Cold-Formed Steel Shear Wall Studs under Uplift Force

Abstract

A cold-formed steel framed shear wall may fail in shear buckling of the sheathing, local buckling or distortional buckling of the framing member under compression forces or connection failures. An unusual distortional buckling mode on boundary studs under uplift forces was recently observed in a shear wall test program conducted at the University of North Texas. It was found in monotonic pushover shear wall tests that the flanges of the boundary studs undertaking uplift forces were distorted at the bottom area of the studs near the hold-down. This paper presents the test program and analysis of the unique distortional buckling mode. The paper also provides procedures for predicting the distortional buckling strength of the boundary studs, as well as the construction details to mitigate the damage by this unexpected distortional buckling mode.