THEORETICAL INVESTIGATION INTO THE LIMITING STATE OF THIN-WALLED STEEL COLUMNS.

It is shown that the behavior of centrally loaded ″actual″ thin-walled box columns is considerably different from the currently held concept of design. The initial imperfections significantly affect the flexure of the bar, the redistribution of load acting on its plate elements, their effective widths and the limiting load of the column. It is concluded that, in comparison with the critical force of the corresponding ″deal″ columns without unavoidable irregularities (the critical force being calculated with due regard to plate buckling), the influence of initial imperfections brings about a substantial reduction of the limiting load.