Influence of perforation pattern in Direct Strength Method of upright design

Abstract

The Direct Strength Method design of thin-walled cold-formed steel members is recently extended to perforated members and implemented in AISI-2016 specification. Albeit the background research is well constructed for discrete perforations, it requires more attention to pattern perforations. Perhaps the range of upright cross-sections and perforation shapes available in the market are patented, is the main reason for the lack of experimental data in this research domain. Available literature reports a pool of numerical data resulting from finite element analysis accounting the parameters such as cross-section shape, thickness, perforation shape, the spacing between perforations, member lengths, etc. These numerical models are mainly calibrated with the experimental results of fixed end columns. It should be noted that the fixed end columns are not influenced by the shift of effective centroid. Using such results in developing analytical equations will end up with the ignorance of effective centroid shift. The systematic experiments on perforated compression members in the view of simply supported boundary conditions are scarce. Therefore, experimental results with respect to flexural boundary conditions are reported herein. With the results of experiments, the influence of perforations is rationally assessed for local, distortional and flexural buckling about minor axis. The interaction between the modes is also observed and reported. The DSM design procedure recommended in the AISI-2016 is validated with the experimental results and summarized for the safe and economic design of uprights. © 2021 Proceedings of the Annual Stability Conference Structural Stability Research Council 2021, SSRC 2021. All rights reserved.