Flexural buckling and design of press-braked rectangular hollow section steel long columns

Abstract

Cold-forming offers several advantages in steel manufacturing over hot forming, including better dimensional accuracy, better control in tolerances and improved quality on product surfaces. A manufacturing process of cold-formed rectangular hollow section suitable for small-scale production involves press-braking and welding, which may bring adverse effects on the structural behaviour of steel structures. In this paper, a comprehensive experimental and numerical investigation on the flexural buckling behaviour of press-braked rectangular hollow section columns has been conducted. Material properties, residual stresses and member out-of-straightness are measured to obtain the basic mechanical properties and imperfections of press-braked RHSs. Seven compression tests on long columns of high strength steel press-braked RHS are conducted. Numerical models are established and calibrated against measured results. An extensive parametric study is conducted and the results are compared with design values provided by various codes of practice. Based on these experimental and numerical results, design recommendations are proposed to the existing design rules. The reliability study has shown that the proposed design rules is effective to predict the flexural buckling resistance of press-braked RHS long columns.