Behavior of cold-formed steel built-up I-sections

Abstract

An experimental investigation was conducted to study the behavior of built-up cold-formed steel studs and to assess the current design provisions of the North American Specification for the Design of Cold- Formed Steel Structural Members. Typical applications include framing for windows, doorways, shear walls, and multi-story cold-formed steel framed buildings in which the lower floor utilizes built-up studs to carry the load. The built-up studs in this study consisted of two C-sections oriented back-to-back forming an I-shaped cross-section. For each specimen, the studs were connected to each other with two self-drilling screws spaced at a set interval. A cold-formed steel track section was connected running perpendicular to each end of the built-up stud with a single self-drilling screw through each flange of the C-sections. The purpose of the track section was to keep the ends of the studs together and represents a common end attachment. As a result of the investigation, the current design requirements were found to be conservative in predicting the ultimate capacity of built-up studs.