ABSTRACT
R, Maquoi Institut du Genie Civil, Universite de Liege, Quai Banning, Liege, Belgium
1. INTRODUCTION
When I and H hot-rolled section beams are either of insufficient strength or are not economic for design, use is currently made of welded plate girders. These are made of steel flats, plates or sheets, usually be welding or bolting but occasionally by riveting; nowadays automatic welding is the most usual means of connection. The main feature of such plate girders - compared to hot-rolled sections - is the very large slenderness of the web, measured by its depth-to-thickness ratio d/ two
Plate girders are structural elements, that primarily resist bending about their strong axis. Because of the slenderness of the web, plate girder sections generally cannot sustain their full plastic bending moment; web buckling very often occurs in the elastic range and thus precedes yielding. In accordance with the generally accepted concept of section classification, plate girders with slender webs belong to class 4 cross-sections (slender sections). For bending, class 4 cross-sections are defined as 'those in which local buckling is liable to prevent the calculated stress in the extreme compression fibre of the steel member from reaching its yield strength' .1
