Tubular construction is synonymous with modern architecture. The familiar range of tubular sections, namely square, rectangular and circular hollow sections, has been recently extended to also include elliptical hollow sections. These new sections combine the elegance of circular hollow sections with the improved structural efficiency in bending of rectangular hollow sections, due to the differing flexural rigidities about the two principal axes. Following the introduction of structural steel elliptical hollow sections (EHS), a number of investigations into their structural response have been carried out. This paper presents a state of the art review of recent research on elliptical hollow sections, together with a sample of practical applications. The following aspects are addressed: fundamental research on elastic local buckling and post-buckling, cross-section classification, response in shear, member instabilities, connections and the behaviour of concrete filled EHS. Details of full scale testing and numerical modelling studies are described, and the generation of statistically validated structural design rules, suitable for incorporation into international design codes, is outlined.

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The global instability of elliptical hollow section members under combined compression plus biaxial bending is studied in this paper by means of laboratory testing and numerical simulations. A total of 9 beam-column tests were carried out under different combinations of compression and bending about both principal axes. The material properties of the tested sections were determined by means of tensile coupon tests. All tested elliptical hollow sections were EHS 150755, and three nominal member lengths of 1 m, 2 m and 3 m were considered. Graphs of applied load versus mid-span bending moment, based on theoretical first and second order elastic considerations and the experimental second order inelastic response, are presented and described. Numerical models were initially validated against the experimental data using measured material and geometric properties, including imperfections. The models were subsequently employed in parametric studies to assess the influence of member slenderness and cross-sectional aspect ratio on the structural response. Finally, based on the experimental and numerical findings, design rules for hot-finished EHS beamcolumns were assessed and statistically verified.