Parametric Stability Analysis of Thin-Walled Polygonal Tubular Members Using the Finite Strip Method

Resumo

This paper presents a parametric study on the stability of steel thin-walled polygonal tubular sections,aiming at typical applications in telecommunication towers. The geometries cover variations in diameter (D),thickness (t), and number of sides (n, from 6 to 20), synthesized through the parameters D/t and relativeslenderness ratios. The elastic critical bending moments and axial loads (Mcr, Ncr) were obtained using the FiniteStrip Method (FSM) through the software FStr Computer Application, with modal identification performed viasignature curves. A predominance of local buckling was observed across the sample, while distortional bucklingoccurred in only two cross-sections under axial compression, precisely those with the lowest D/t ratios. In termsof overall trends, increasing D/t led to reductions in Ncr and Mcr. Normalization by plastic reference quantities(Ncr/Ny, Mcr/My) and the use of relative slenderness parameters substantially reduced data dispersion andproduced consistent results, according with classical design formulations. As the main contribution, this workprovides and discusses the key trends related to the influence of geometric parameters on the stability of polygonaltubular sections under compression and bending. Finally, comprehensive normalized results on the structuralperformance of cold-formed, thin-walled steel polygonal members are presented, with a focus on engineeringapplications for posts supporting telecommunication antennas.