Optimization of steel sections according to Eurocode 3 provisions

The paper deals with the optimal design of steel sections of large span beams. Since deep section behavior is strongly conditioned by adverse effects of local buckling in compressed panels, many technical codes such as the Eurocode 3 (EC3), adopt specific dimensional constraints in order to reduce problems connected to section instability. In particular, EC3 divides steel sections into different classes depending on their vulnerability to local buckling, and commercial profiles are classified according to dimensional limits provided by codes. When large size elements are used, no standard sections are available, and the compactness of each panel has to be specifically designed complying with the code prescriptions. In this case, the common approach of scaling the commercial sections and then applying the required slenderness limits may not lead to the best design since the obtained geometry, generally, is not the most suitable and economic. The present work is aimed to support the design of high size sections, according to the current codes. A composed I shaped steel section, having an internal stiffener which divides the web into two panels of different thickness, has been considered and compared with two more conventional I shaped sections. The obtained results allow to draw some interesting information concerning the optimal geometry of deep sections.