Elastic local buckling formulae for thin-walled I-sections subjected to shear and direct stresses

Formulae for calculating the elastic local buckling stresses of doubly-symmetric thin-walled I-section girders subjected to combined shear and direct stresses, accounting interaction between plate elements are presented. The (i.e. flanges web) is bounded by a theoretical lower-bound, where there no critical considered be simply-supported, upper-bound strongest have rotationally fixed edges. accounted introducing an coefficient ζ that quantifies relative level fixity aforementioned lower upper bounds. Expressions calculate calibrated using results from finite element analyses generated in Abaqus . Doubly-symmetric I-sections varying geometric proportions loaded shear, major axis bending, compression full range combinations thereof considered. Using developed formulae, studied cross-sections accurately predicted, typically within 5% values obtained FE models; this significant improvement over determined traditional manner which effects ignored, cross-section stress shown underestimated as much 40%. • Elastic under determined. Interaction restraint boundaries. predicted results. Buckling also accurately. Significantly improved predictions when compared current EC3 provisions.