Numerical modelling of rectangular cold-formed steel and composite columns

Abstract

Cold-formed hollow sections have a lower resistance capacity than hot-rolled profiles due to their welded seams. However, using design codes for such sections usually leads to an uneconomical and conservative structural design for compressive members. This paper presents a series of numerical analyses of standard and concrete-filled cold-formed columns to understand and evaluate their performance. A numerical model was developed calibrated against experiments considering residual stresses, initial geometric imperfections and material properties. The developed numerical model was able accurately to represent the experimental results in terms of failure mode, deformed shape and compressive resistance. Based on these results, an alternative buckling curve is proposed for plain steel and steel–concrete composite columns. This design curve was determined from the results of a parametric study and led to the use of new values of imperfection factor and initial non-dimensional slenderness for the Eurocode design procedure. A reliability index was also evaluated to estimate the scope and validity of the proposed curves.