Automatic cross-section classification and collapse load evaluation for steel/aluminum thin-walled sections of arbitrary shape

• Thin-walled sections of arbitrary shape subject to axial force and biaxial bending.
• Automatic conversion between different descriptions of the section geometry.
• Evaluation of cross-section collapse load and classification according to Eurocodes.
• Employment of two algorithms for nonlinear and rigid-plastic constitutive laws.
• Numerical comparisons and new analyses show effectiveness of both algorithms.

We present a computational procedure for evaluating the collapse load and assessing the cross-section classification of thin-walled sections of arbitrary shape on the basis of Eurocode prescriptions. The procedure is based on two algorithms which address separately the rigid-plastic model adopted by the Eurocode for ordinary steel cross-sections and arbitrary uniaxial constitutive laws typically used for stainless steel and aluminum. Both algorithms are based on a polygonal description of the cross section boundary so that integrals extended to the section domain are conveniently expressed as algebraic sums depending upon the coordinates of the section vertices. Accordingly, a further algorithm is illustrated in order to automatically convert the plate and node model adopted by Eurocode to a polygonal description of the section geometry. The numerical effectiveness of both algorithms is assessed with reference to an I-shaped, a Z-shaped and a RHS cross sections.