Global stability calculation procedure of solid$-$web axial compression member

$[$Exercise $6\mathrm{.}3]$ Design a welded H$-$type section axial compression column, the steel is Q$235$B$,$ the column bears the design value of axial compression load $N=400kN,$ the column upper and lower ends are hinged, the height of the axial compression column $l=6\mathrm{.}00m,$ the height middle does not set lateral support. Flange plate for flame cutting edge. No cross section weakening.