ABSTRACT
is the effect of filling the tube with a rigid material such as concrete. It can be seen that all currently rolled sections will carry yield stresses in each axis before buckling. In two cases constituent plates are in class 3 and would therefore be incapable of showing any ductility following the achievement of yield. Filling these sections with a rigid material such as concrete raises their class one level and would allow some redistribution of moments in frames or continuous beams formed with these elements. The ductility of other sections can be improved from class 2 to class 1 by infilling the section. This would allow full plastic analysis to be used for frames that utilise filled elements such as these.
