Resistance of cold-formed high strength steel circular and polygonal sections - Part 2: Numerical investigations

• Numerical investigations on the resistances of cold-formed high strength steel circular and polygonal sections were performed.
• Influences of offset yield strengths on the FE Analyses were investigated.
• Effects of the polygonal cross-sections' folding zones on their buckling behaviour were presented.
• Sensitivity to geometrical imperfections in the numerical models was analysed.

This paper is the second part of the study on the cold-formed high strength steel circular and polygonal sections intended to be used in tubular wind towers. Results from 32 numerical finite element analysis (FEA) models were compared with and calibrated against results of the tests on 32 corresponding specimens. The FEA results agreed well with the experimental results in terms of resistances and load-displacement curves. Further investigations on the numerical models were performed. Yield stress used in the FEA significantly affected the resistances of the numerical models. Using 0.2% proof stress leaded to higher resistance than the experimental results. Corners significantly influenced buckling behaviour in the polygonal section models. Analyses of an oval opening in the tubular specimens showed that peak stresses around the opening were considerably higher in the polygonal section models than in the circular section models. Finally, investigation of sensitivity to geometrical imperfections indicated that failure modes of numerical models with geometrical imperfections according to EC3 significantly differed from those of tested specimens and numerical models with geometrical imperfections obtained from the 3D scans.