Advances in direct strength design of thin-walled members

摘要

The use of the finite strip method for elastic buckling prediction has provided significant insight into the behavior of thin-walled cold-formed steel members. To date, many of those insights have not been fully incorporated into design specifications, e.g., the North American Specification for the Design of Cold-Formed Steel Structural Members (AISI 2002) provides no guidance on distortional buckling and ignores interaction of elements in local buckling. The Direct Strength method is an attempt to integrate known elastic buckling behavior of thin-walled members, including local, distortional, and global buckling modes, into a design framework that is efficient and reliable. The method does not employ effective widths, nor require iterative section property calculations, and as a result is a significant departure from conventional thin-walled design. Work on laterally braced beams and pin-ended columns has shown the efficacy of the approach. Beam-columns provide an area where further study is underway.