Optimization of steel structures

Typically in the optimization of steel structures, the weight of the structure is chosen as the objective. When comparing different steel grades, the total manufacturing cost is a more relevant criterion than weight, as has been pointed in other applications, as well. The material costs are typically 40 % of the total costs of steel structures. The manufacturing costs depend roughly on the steel material costs and actions which are needed in manufacturing. The material costs of HSS have been given in up to the steel grade S1000 based on interviews of five European steel fabricators. In this research, the same relational material costs were accepted for HSS by taking as a reference to the regular steel S355. In the action time, based calculation method to calculate the manufacturing costs of structures is proposed. A similar method has been used in. In all of these, the manufacturing costs were calculated based on a generic feature-based cost calculation method including costs of all actions in the workshop. In the developed method has been compared with a non-feature-based method of using data of an actual project. The authors are not aware of a cost calculation method that covers the data for steel grade up to S960. In this study, the industrial partners of the research project estimated the cost factors for manufacturing concerning S355 such that S960 could be included in the comparison. Optimization of typical steel structures, such as beams, columns and trusses, has been the subject of numerous research papers. Optimal properties for I-shaped beams have been considered since up to recent studies including steel grades up to S700 and hybrids where the flanges are made of different steel grades than the webs. Hybrids have shown to be cost-effective solutions for beams. Up to up to 34% weight savings for welded I-beams (WI-beams) were obtained with large loads, whereas about 10 % of cost savings were found using HSS instead of S355. In beams, the SLS may become critical, but using pre-camber, as is possible for welded beams, the deflections can be reduced. Welded box beams (WQ-beams) with wide bottom flanges are frequently used solutions in slim floors, especially in Scandinavia. Optimum solutions for WQ-beams using HSS is still a rather open question. Welded box (WB) columns include the possibility to use hybrid solutions but the optimal solutions for these are not known.