ABSTRACT
The use of elliptical structural forms dates back to the mid-nineteenth century. In the initial designs of the Britannia Bridge developed in 1845, elliptical sections were considered for the compression flange of the main box girder (Ryall 1999), whilst the primary arched compression elements of the RoyalAlbert Bridge, designed by Brunel and constructed in 1859, were of elliptical form and fabricated from wrought iron plates (Binding 1997). Elliptical hollow sections (EHS) are now available as hot-rolled and cold-formed structural sections and have recently begun to appear in steel construction. Examples include several canopies and buildings, such as the coach station at Terminal 3 and the main building at Terminal 5 of Heathrow Airport in London (McKechnie 2006) and the main building at Terminal 4 of Barajas Airport in Madrid (Viñuela & Martinez 2006), as well as bridges, such as the Highland Society Bridge in Braemar, Scotland (Corus 2006). From an architectural perspective, these new sections offer an interesting and unusual appearance, whilst from the structural standpoint, they possess differing flexural rigidities about each of the principal axes (allowing the sections to be orientated to most efficiently resist the applied loading) as well as high torsional stiffness.
