Evaluation of European approaches applied to design of TWCF steel members

Thin-walled cold-formed (TWCF) steel members are widely used in aerospace, automobile and architecture industries. Among the various advantages, mainly associated with the relatively simple and very cheap techniques required for their production and shaping, it is important to mention the relevant high strength to weight ratio. Beside the benefits, it has to be pointed out that the TWCF member response is quite difficult to be predicted because of the significant influence of local, distortional and overall buckling phenomena, owing to the frequent presence of open mono-symmetric cross-sections.The present paper can be intended as a typical technical paper whose results are useful not only for research activities, but, especially, for the routine design. It summarises a study aimed at increasing the safety of two European approaches that should be potentially adoptable for designing TWCF steel members. The grade of reliability of these existing European procedures has been evaluated by predicting the performance of more than 240 TWCF members tested in laboratory, selected in the framework of 13 experimental studies, taken from the literature. Being the assessed load carrying capacity sometimes significantly greater than the characteristic experimental one, suitable safety factors have been consequently calibrated and proposed for each cross-section type, to be directly adopted in routine design to match the requirements associated with the limit state philosophy. Finally, the strength of additional TWCF beam-column specimens has been predicted to assess the efficiency of the proposed coefficients for practical cases frequently encountered in routine design. A complete benchmark is proposed in Appendix A, where the application of the considered design procedures for one selected case is reported.