Use of Ramberg-Osgood material laws in the finite element modeling of cold-formed tubes

摘要

The present paper investigates the cross-sectional resistance of cold-formed tubes; in particular,rnattention is paid to the influence of various material laws on the carrying capacity. Owing to the fabricationrnprocess, coupons from cold-formed tubes usually exhibit a rounded stress-strain relationship, whose shape isrnknown to be influenced by many parameters, such as the cross-sectional width-to-thickness ratio and the locationrnof the coupon within the section or the type of steel. The intention is here to bring out to which extent the materialrnlaw may affect the structural response of such cold-formed tubes, with respect to relevant parameters. The paperrnfirst analyzes several tensile test results, and proposes Ramberg-Osgood equations with adjusted parametersrnevaluated from experimental results. Suitable shell FE models are then used to characterize the influence of thernmaterial response roundedness on the cross-section resistance. Eventually, recommendations are proposed for arnsound modeling of cold-formed tubes in FE analyses.