Plastic Behavior of Hollow Structural Sections

Abstract

A series of tests on beams of hollow structural sections was conducted to determine their adequacy in plastic design. A minimum plastic rotation requirement of law times the elastic limit rotation prior to unloading below the fully plastic moment was used to separate sections into categories of plastic and allowable stress design. Local buckling caused by high residual stresses occurred for all but the very stocky sections (b/t<15, in which b=flange width and t=thickness). The recommended slenderness limit is given by b/t<150/(σo)1/2, in which σo=yield stress) a value considerably less than is currently recommended by CSA-S16 (1969) or AISC (1970).