ANÁLISE DA INTERAÇÃO ENTRE OS MODOS DE FLAMBAGEM LOCAL E DISTORCIONAL EM PERFIS DE AÇO FORMADOS A FRIO COM SEÇÃO RACK

Resumo

Buckling modes interaction is a quite frequent behavior of cold-formed steel members, conducting to
structural strength reduction. Local, distorcional and global buckling modes are considered in design standard and
code procedures of steel cold-formed members, according with widely accepted rules, as those included in the
direct strength method, DSM, and the effective section method, ESM. The former has been incorporated by
different standards in many countries and the latter is part of the Brazilian code NBR 14762:2010. Anyway, the
design rules available in these standards offer solution only for local-global buckling interaction.
The local-distortional buckling interaction, LD, is the focus of the present research, addressed to the particular
case of rack section columns, usually applied in storage rack systems. The investigation takes into account previous
results for LD buckling interaction for lipped channel columns available in the literature, including the results of
recent researches developed by the Thin-Walled Structures research group from COPPE-UFRJ. The present study
is based on (i) the development of a shell finite element method numerical model, calibrated with the help of
experimental results available from previous investigations; (ii) development of parametric analysis covering LD

interaction of CFS rack columns with wide variation of geometry and slenderness; (iii) examining proposed DSM-
based formulations in the literature to predict CFS lipped channel columns strength, and its applicability to rack

sections. Based on the results obtained through FEM modeling of 210 columns, it was found that the DSM
approaches proposed for lipped channel columns lead to appropriate and accurate results in the case of rack
sections.