Local buckling strength of closed polygon folded section columns

Abstract

Abstract The local buckling behavior of regular polygonal, short length steel columns, fabricated by welding two half sections made of folded steel plates, is described. The polygonal sections are composed of five different section profiles with four to eight sides and each profile having component plates with one to four varied width-to-thickness ratios. A total of 15 specimens are used in the compression test, sustaining uniform compression stress in the fixed end condition. Accurate measurements of welding and cold-forming residual stresses and geometric imperfections were taken prior to testing and are presented in this paper. The test strengths are compared with the current plate buckling code in Japan and with the ECCS recommendations for unstiffened circular cylinders. The empirical design formula based on the test data is also presented to predict the local buckling strength of the polygonal section columns.