Design of planar semi-rigid steel frames using genetic algorithms and Component Method

• A practical numerical method for the design of planar steel frames is proposed.
• A new fitness function which does not use penalty coefficients is proposed.
• The procedure has been simplified where possible to reduce the computational cost.

This paper presents a practical numerical method, based on evolutionary computation techniques, for the optimum design of planar semi-rigid steel frames. A genetic algorithm provides the optimum steel shape for each member of the structure and for the optimum semi-rigid joints between members, taking into account discrete variables related to several sets of steel shapes, bolt diameters and steel plate thicknesses. The objective function includes the combined cost of members and semi-rigid joints. Constraints related to both service and strength load levels are included. The behaviour of the semi-rigid joints between the columns and beams is obtained by means of the Component Method detailed in Eurocode 3. As examples, two structures are designed to demonstrate that the proposed design method is a practical procedure for the minimum cost automated design of planar semi-rigid steel frames.