DESIGN OF TOP CHORD OF STRESSED-ARCH FRAMES

Stressed-arch frames are characterized by a posttensioning procedure t hat is used to erect the frames from an assembled configuration at gro und level to a final erected shape. During the erection process, the t op chord becomes curved and is usually stressed into the inelastic ran ge. Consequently, the strength of the erected frame under service load ing cannot be assessed rationally using conventional elastic or plasti c methods for the analysis and design of steel structures. The purpose of this paper is to examine in detail the provisions of the Australia n Standard for Steel Structures, AS4100-1990, and the 1993 American In stitute of Steel Construction Load and Resistance Factor Design Specif ication (AISC LRFD) for the design of the top chord of stressed-arch f rames, and to propose and validate a simple design procedure. In parti cular, the irrationality of to propose and validate a simple design pr ocedure. In particular, the irrationality of design based on conventio nal elastic and plastic methods, and, alternatively, the rationality o f design based on advanced analysis as described in AS4100-1990, is id entified.