If elastic cross-section capacities are exceeded, plastic cross-section reserves can be taken into account. In the detail settings of the STEEL EC3 add-on module, you can activate the STEEL Plasticity module extension.
Whether it is a "partial internal force method according to Kindmann" or a "simplex method," the module extension provides the appropriate design method for all sheet cross-sections.
(Thus, it is not only possible to design structures more economically, but also better statements referring to the ductility of the structure can be made.)
In combination with the STEEL Warping Torsion module extension, you can perform plastic design according to the second-order analysis with 7 degrees of freedom.
As usual, you can print all designs of the plastic design in the central printout report of RFEM or RSTAB.