High-strength steels in steel structures: How to select the appropriate steel grade?

Among the existing solutions to reduce material consumption in the construction sector, the steel market is continuously witnessing the emergence of new, ever-stronger steels. The recent improvements of the steelmaking process have indeed enabled to manufacture wide flange sections with improved material properties, with good toughness and weldability performance. The development of high-strength steels contributes to the optimisation of structural designs with the potential for substantial weight, cost and carbon savings. Hot-rolled sections with a yield strength of up to 500 MPa in Europe and 80 ksi (550 MPa) in the United States already exist and comply with the product standards for structural applications. Although research has shown an insignificant increase in carbon footprint with rising yield strength, demonstrating the environmental benefit of developing and using higher steel grades, their adoption remains quite marginal. This can be explained by a lack of information on existing high-performance products and the advantages they offer, as well as a lack of availability resulting from the current low demand for these grades. In addition, higher steel grades are often associated with increased unit material costs, reduced weldability and ductility, and a greater tendency to both local and global buckling instabilities. Consequently, designers are often reluctant to incorporate these innovative materials in their designs and manufacturers hesitant to develop them, particularly in the absence of clear guidelines for assessing their economic viability in specific structural applications. This paper consists of a comparative study on the use of the appropriate steel grade for members under pure compression. In particular, reference member slenderness ratios are established allowing the identification of the relevant field of application for the different considered grades.