Sustainable design of high-strength steel structural components : process-based life cycle assessment with uncertainty and sensitivity analysis

Abstract

High-strength steel (HSS) components are increasingly used in building construction due to their exceptional strength-to-mass ratio (S-M-R), required ductility, outstanding durability, excellent toughness, and enhanced resistance to corrosion and fire. These components reduce material usage, production, transportation, sawing, painting, and welding requirements. However, the sustainability of HSS versus conventional steel under equivalent design loads remains unexplored. This study used process-based life cycle assessment (LCA) to compare the environmental performance of topologically optimized HSS columns and beams (S460 and S690) produced through quenched and tempered (QT) and thermo-mechanically controlled processing (TMCP) with S355. The results showed reduced environmental impacts for HSS columns (13.10 % and 26.54 % for QT; 14.82 % and 29.83 % for TMCP) and HSS beams (9.21 % and 23.52 % for QT; 9.90 % and 26.99 % for TMCP) compared to S355. Overall, HSS columns demonstrated greater environmental benefits than HSS beams, and the TMCP method showed more significant environmental advantages than the QT method. To further assess the reliability of these findings, a Monte Carlo analysis was conducted to evaluate the uncertainties associated with inventory data. In contrast, sensitivity analysis identified critical parameters influencing environmental impacts. These analyses ensured the robustness and reliability of the results presented under conditions of data, model, and assumption variability. Sensitivity analysis identified steelmaking and raw materials processes as key factors due to energy consumption. TMCP-produced HSS columns proved more sustainable than QT-produced alternatives. Steelmaking contributed 94.02 % and 93.78 % of the global warming potential (GWP) for the S460-QT and S690-TMCP columns, respectively. Critical parameters included chemical composition, production process, mass reduction, electricity mix, and corrosion resistance. The results indicate that HSS can reduce CO2-eq emissions in the construction industry, thereby supporting its transition toward net-zero emissions.