Minimum Cost Design for Fire Resistance of Welded Steel Structures

The optimum design is applied to cost minimization of two types of welded steel structures in fire. Both unprotected and protected structures are investigated. The compressed rod of welded square box cross-section is designed to overall and local buckling. The bent beam of welded box section should fulfil the stress, deflection and local buckling constraints. The cost function consists of the cost of material, assembly, welding, painting and fire protection. In the unprotected case the critical temperature method is used with formulae given in Eurocode 3. For both structures investigated the protected one is cheaper than the unprotected. This difference is attributed to the significant difference in thicknesses.