Tolerances of imperfections and strength of cold-formed lipped channel column

The paper addresses the ultimate buckling strength of thin-gauge axially loaded lipped channel columns with initial geometrical imperfections related to execution tolerances. For computational modelling of the column strength respecting the tolerance limits a deterministic method employing geometrical and material nonlinear FEM analysis with imperfections (GMNIA) is suggested. The imperfections are assumed in the shapes of eigenmodes of the corresponding linearized buckling problem and their combinations. For comparing their influence on the column strength, the imperfections are normalized by the energy measure. The comparison is carried out on the top energy measure level limited by execution tolerances. Referring to published experimental work three cross-sections and several column lengths are considered in a numerical study. Summarizing the numerical results and abilities of the energy measure to facilitate the treatment, guidance for the use of FEM GMNIA in the estimation of the column least strength is suggested.