Structural design using cold-formed hollow sections

This paper reviews the differences between the alternative types of structural hollow section products (cold-formed versus hot-finished) as they affect structural design in Europe, using the relevant product and design standards, with an emphasis on Rectangular Hollow Sections (RHS). Manufacturers of cold-formed structural hollow sections (CFSHS) are more numerous, so that their products are more widely available. Hot-finished structural hollow section (HFSHS) products are typically between 24 % and 54 % more expensive in Germany than their cold-formed counterparts, the lower differences being for large tonnages - a strong inducement in favour of CFSHS. The price difference may also vary within the European Union. The geometric and product properties which are distinctly unique to CFSHS are presented and shown to offer no restrictions in their use when in compliance with the appropriate clauses in the European standards. These are the influence of corner radii, welding in the corner area, material choice to avoid brittle fracture and suitability for welding CFSHS. A comparison of the structural performance of CFSHS and HFSHS shows equally efficient structural designs for both products. The points covered are the design of compression members - unfilled and concrete-filled, joint resistance - which typically governs selection of member sizes, as well as fatigue design, fire design and the resistance of braced steel frames to severe seismic loading. CFSHS are shown to be adequate under all these situations.