Numerical study on bending behaviour of hot-finished and cold-formed elliptical hollow sections

Elliptical hollow sections (EHS) are new products on the construction market. Their growing implementation in steel structures led to complementing design rules in the draft version of Eurocode EN 1993-1-1:2015. In this paper bending strength of elliptical hollow sections is being discussed, analysing cold-formed and hot-finished EHS profiles under pure bending. Numerical models include short members of diverse section slenderness with applied concentrated moments at the ends about either the major or the minor axis of inertia. Material nonlinear behaviour is included through experimental tensile test results adopted from previous researches. Influence of geometrical imperfections is incorporated in the analysis, however, imperfection amplitude variation has shown an insignificant effect on bending strength. For all analysed members, it is shown that numerically obtained ultimate moments are higher than bending strengths prescribed in EN 1993-1-1:2015. Differences in responses of hot-finished and cold-formed EHS are discussed. Comments on elliptical cross-section classification according to the design standard are made, as well as comments on the defined effective cross-sectional geometrical properties. Review of the set limiting slenderness for class 3 is suggested.