Simple design procedure for the cold-formed tubular top chord of stressed-arch frames: Fid-Bau Portal

Simple design procedure for the cold-formed tubular top chord of stressed-arch frames

Clarke, Murray J. / Hancock, Gregory J.

AbstractStressed-arch frames are characterized by a posttensioning procedure which is used to erect the frames from an assembled configuration at ground level to a final erected shape. During the erection process, the cold-formed tubular top chord becomes curved and is usually stressed into the inelastic range. Consequently, the strength of the tubular top chord under the additional axial compression arising from service loading cannot be assessed rationally using conventional methods for the analysis and design of steel structures built from either hot-formed or cold-formed members. This paper proposes and validates a simple design procedure for the cold-formed tubular top chord of stressed-arch frames. The possible provisions of the American Iron and Steel Institute Load and Resistance Factor Design (AISI LRFD) Specification for the design of the top chord are described briefly, although the basis of the proposed design procedure is the advanced analysis provisions of the Australian Standard for Steel Structures, AS4100–1990. In order to accommodate the rational and economical design of unconventional cold-formed steel structures such as stressed-arch frames, for which conventional analysis/design approaches are inappropriate, it is suggested that the advanced analysis/design philosophy should be incorporated into the proposed Australian Limit States Standard for cold-formed steel structures.