Abstract
Eurocode 3 (DD ENV 1993-1-1 : 1992) provides design guidance on the stability of restilinear (beam and column) structural frames but it does not embrace the design of slender monotubular 'curvilinear) arches, since it provides no information on geometric imperfections, for such arches. This has arisen as a significant limitation in the preparation by CEN-TC 284 of a draft European standard for the designof greenhouses, since slender arches formed from a cicular hollow steel section tube are used extensively throughout Europe in the production of "tunnel greenhous", or "polytunnel" frames. Slender arches are also used increasingly in garden-centre and emergency-aid structures, as an architectural feature in glazed barrel-vaulted roofs, and for swimming-pool covers. To address the immediate requirement for rational design procedures for slender steel arches used in polytunnel greenhouses, collaborative research involving full-scale collapse testing, determintation of tube behaviour, and computational modelling has been undertaken recently in France ad the UK.