Numerical Analysis on Distortional Failure of Cold-Formed Steel Hat- Section Beams under Non-Uniform Bending

Resumo

Cold-formed steel (CFS) members stand out among steel structures notably due to their lightness,
structural efficiency (high strength-to-weight ratio) and versatility. However, given their high width-to-thickness
ratio, CFS are highly susceptible to instability phenomena (buckling). The objective of this research is to analyze
the structural behavior of cold-formed steel hat-section beams under non-uniform bending about the major and
minor-axis, regarding the risks of distortional failure. Through the Generalized Beam Theory (GBT), using the
computational program GBTUL, the geometries where the distortional failure is predominant were selected,
presenting: distortional modal participation (Pdist) greater than 85% and distortional critical buckling moments
(McrD) significantly below their local (McrL) and global (McrG) counterparts. The beams were analyzed for two
end support conditions that differ only by the restriction to warping (free or prevented), and were subjected to
moments at the end sections, constituting different loading hypotheses. Through the computational program
ABAQUS, a shell finite element model was developed to perform the buckling analysis on the selected elements.
The results obtained with the model present appropriate values and the expected behavior, indicating that it
adequately simulates the elements. In addition, they demonstrate how support conditions and loading affect the
distortional critical buckling moments.