The design of slender monotubular steel arches

• Published in: Structural engineer (London, England : 1988) England : 1988), 1997-05, Vol.75 (9), p.143-151
• Main Authors: Roux, P., Robertson, A.P., Motro, R.
• Format: Article
• Language: English
• Subjects: Environmental Sciences
• ISSN: 1466-5123

Eurocode 3 (DD ENV 1993-1-1 : 1992) provides design guidance on the stability of rectilinear (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 design of greenhouses, since slender arches formed from a circular hollow steel section tube are used extensively throughout Europe in the production of " tunnel greenhouse ", 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, determination of tube behaviour, and computational modelling has been undertaken recently in France and the UK. This paper summarises the ultimate limit state design philosophy of Eurocode 3 and reports on the development of compatible design methodologies for slender greenhouse arches. These include the provision of geometric imperfections and critical load factors which have been derived from the results of a number of full-scale collapse tests on individual, unclad, polytunnel arches under simulated snow and wind loading. Computational analyses ranging from first-order, elasto-plastic with a refined plasticity model have been conducted to derive the necessary design data. The proposed methodologies have been developed to reflect as closely as possible the procedures and philosophy of Eurocode 3. It is envisaged that, initially, this new information will be contained in the forthcoming European standard on green house design (due to be released for public inquiry early in 1997), but that ultimately it may form the basis to extend the scope of Eurocode 3 to include the design of slender arches. L'Eurocode 3, (DD ENV 1993-1-1:1992) fournit des règles de vérification de la stabilité des éléments structurels rectilignes (poutres, poteaux), mais il ne couvre pas la vérification d'arceaux monotubulaires élancés dans la mesure où il ne fournit aucune information sur les imperfections géométriques, les longueurs de flambement ou les moment de déformation latérale amplifiés pour de tels arceaux. Ceci a conduit à