Buckling Strength of Lipped Channel Column with Local/Distortional Interactions

Two approaches to the choice of the most unfavourable geometric imperfections, represented by the eigenmode shapes, recently developed for GMNIA FEM analysis are studied for lipped channel columns exhibiting significant local/distortional interactions. The approaches are based on alternative imperfection measures: a) the commonly applied amplitude, b) the energy measure defined by the square root of the elastic strain energy hypothetically required to distort the originally perfect structural element into the considered imperfect shape.