Elastic local buckling of three-flanged cross-sections

In current structural steel design specifications, the local buckling of cross-sections is typically treated on an element-by-element basis, with boundary conditions along adjoined longitudinal edges individual plates assumed to be simply-supported. reality, buckle locally as a whole and plate elements interact. As result, critical isolated (i.e. that lowest elastic stress) lie between lower upper bounds simply-supported fixed, respectively. Based this concept, explicit formulae predict stress full common profiles, including I-sections, have recently been developed (Gardner et al., 2019) [1]. present paper, for single I-sections set out in Gardner al. (2019) [1] are extended cover case three-flanged arise longitudinally-stiffened girders haunch apex regions portal frames. The geometry loading studied remain constant member length, i.e. influence tapering moment gradients not considered herein, but has evaluated parallel work (Quan 2020) [2]. proposed calibrated against results from finite strip analysis performed using CUFSM v4.05 (Li Schafer, 2010) [3] range sections, provide predictions stresses within 5% numerically obtained values.