Nonlinear Analysis on the Distortional-Global Couple Phenomenon in Cold-Formed Steel Lipped Channel Columns

Resumo

The objective of this work is to understand the distortional-global (DG) buckling interaction of cold-
formed steel (CFS) lipped channel (LC) columns in its post buckling structural behavior and strength. There are a

few studies conducted on this topic in the literature, and the present study can be a motivation to encourage new
design procedures for CFS structures. The research program included the development of a FEM model, which
allowed detailed study of the DG buckling interaction and the comparison of the obtained results with usual design
procedures. In order to perform elastic buckling analysis, a software entitled FStr Computer Application was
developed, based on the finite strip method. The developed computational program is able to generates the
buckling mode geometry to be inserted as the initial geometric imperfection (IGI) in the shell finite element model.
Furthermore, the nonlinear analysis carried out stability paths for different combination of IGI of global and
distortional buckling modes. This IGI combination helps to understand the DG buckling interaction in a wide range
of cases. A parametric study varying the column’s length has demonstrated that the nominal column strength
equation for global buckling, presented in ABNT NBR 14762:2010, is enough to cover the DG interaction.