Initial imperfection sensitivity analysis of lipped channel columns at high temperatures

An imperfection sensitivity analysis is carried out on laterally restrained cold-formed thin-walled lipped channel columns. The equations given in Eurocode 3: Part 1.3 and FE-analyses are used to evaluate the flexural buckling strength and ultimate strength of the sections. The analyses are performed at both room and fire temperatures by introducing corresponding material data values obtained from high temperature transient tensile tests into the models. The purpose of the study is to evaluate the possibility of using normal temperature design formulae directly also at high temperatures and to evaluate the influence of the choice of initial geometric imperfections on the modelled behaviour of the columns. The different local and global stability phenomena and their influence on the post-buckling strength are specifically considered in this study.