Optimised steel frame design using reclaimed steel: Logistics impact on reuse efficiency

Abstract

Structural steel reuse offers significant environmental benefits by reducing demand for new materials and minimising recycling energy. However, implementation is hindered by uncertainty in stock availability, pre-existing defects, and logistical challenges, particularly transportation. This paper applies a sustainability-driven discrete sizing optimisation framework, using Mixed-Integer Linear Programming (MILP), to minimise the environmental impact of steel frame construction using both new and reclaimed steel. The framework integrates structural analyses and design limit state checks, with an environmental objective function covering demolition, deconstruction, fabrication, assembly, and transportation. Key parameters, including total environmental impact, structural weight, reuse rate, allowable oversizing, and the effect of excluding damaged items, are investigated in the context of transportation logistics for a benchmark four-storey steel frame. Results from 625 simulated stock scenarios show that while higher reuse rates generally reduce environmental impact, logistical factors strongly influence benefits. Increasing transport distances for reclaimed steel can reduce its environmental advantage by over 30 % on average, making mixed designs of new and reclaimed steel optimal in more cases. Excluding damaged items significantly affects environmental performance, highlighting the need for research and regulation on reusing defective steel. Additionally, upper thresholds of the overweight ratio for the global frame and individual members were identified, within which reuse efficiency is maintained despite oversizing. These findings support industries in optimising resources for sustainable steel reuse, reducing environmental impact, material waste, and lifecycle costs.