Optimization of open cross section of the thin-walled beam with flat web and circular flange

This paper is devoted to cold-formed thin-walled beams with open cross section. The beam cross section is optimized for a fixed cross section area under strength and stability constraints. Optimal geometrical parameters of the cross section are determined with regard to maximal and safe bending moment. The strength condition is a classical condition applied to the theory of beams for assumed allowable stress. The stability condition serves also as a classical condition for lateral buckling, taking the warping torsion into account. Moreover, the thin-walled beams have been analyzed, for which the shear center, i.e. the main pole, is located in the centroid of the cross section. Results of the numerical analysis are given. Figures present examples of optimal cross sections of the thin-walled beams.