By integrating life cycle assessment with intelligent optimization, researchers show how data-driven design can turn reclaimed steel into a truly sustainable alternative without compromising strength or performance.
Study: Optimized steel frame design using reclaimed steel: Logistics impact on reuse efficiency. Image Credit: Kub The Shadow Simple Man/Shutterstock.com
Researchers have recently introduced a sustainability-driven optimization framework to evaluate the environmental efficiency of steel frame construction using reclaimed steel. This framework integrates Mixed-Integer Linear Programming (MILP) with Life Cycle Assessment (LCA) to analyze how logistics, oversizing, and material damage affect reuse efficiency.
Published in the Journal of Constructional Steel Research, the study simulated 625 stock scenarios for a benchmark four-story steel frame. The findings highlight that while higher reuse rates generally lower environmental impacts, transportation logistics and material condition significantly influence the sustainability of reclaimed steel in construction.
An Overview of Steel Reuse in Construction
Steel is a backbone of modern construction, valued not just for its strength and flexibility, but also for how easily it can be reused or recycled.
In a 2014 survey of UK demolition contractors, an impressive 96 % of structural steel was recovered: 5 % was reused as-is, while 91 % was recycled. Recycling does cut down on the need for new raw materials, but it still takes a lot of energy to melt steel down and process it again. Reusing steel, by contrast, keeps all the energy that went into making it in the first place - and skips the remelting process entirely - making it the greener choice overall.
However, steel reuse faces challenges, including supply chain constraints, high deconstruction costs, and inconsistent component availability.
Non-standard dimensions, limited modularity, and uncertain material properties further complicate reuse. Scientists suggest strategies such as non-destructive testing, geometric characterization, and Design for Deconstruction (DfD) to promote easier disassembly and reuse of structural components.
The Study
The proposed framework integrates structural analysis with MILP to minimize the environmental impact of steel frame construction.
In the study, the team chose to focus on a four-story gravity frame commonly used in low-rise residential buildings across the UK and Europe. Each story was 3 meters high, with four bays spanning 6 meters each. This setup reflects a typical low-rise gravity system, featuring pinned connections and no contribution to lateral resistance - essentially a standard configuration for buildings of this type.
The framework uses a two-tier design loop to meet both ultimate (ULS) and serviceability (SLS) limit states. It starts with initial member sizing, followed by structural analysis in OpenSees to calculate internal forces and deflections.
A mixed-integer linear programming (MILP) model then optimizes the selection of members from available stock. This process iterates, updating the structural model each time, until results converge. If deflections exceed acceptable limits, additional constraints are applied to rule out sections with inadequate bending stiffness.
Environmental impact is evaluated using the ReCiPe method, which consolidates 18 midpoint indicators into three overarching categories: human health, ecosystems, and resources. This produces a single environmental impact (EI) score, allowing for straightforward comparisons between design alternatives.
The total EI includes emissions and impacts from demolition, production, deconstruction, reconditioning, fabrication, assembly, and transportation. Binary decision variables determine both member assignments and whether materials are classified as waste. Additional constraints account for off-cut lengths and emissions related to transport.
Key Findings
The outcomes demonstrated a complex interplay between reuse rate, transportation logistics, and structural design parameters.
Designs utilizing reclaimed steel consistently demonstrated lower environmental impacts than those using new stock, achieving reductions of 64–67 %. These values correspond to environmental impact ratios of 0.33–0.36 when comparing reclaimed (baseline) to new steel designs. Under equal prefabrication distances (Δd = 0 km), reclaimed steel-based designs recorded 268.2–375.1 ReCiPe points, compared to 739.8–1121.2 for new stock designs.
Higher live loads required stockier sections, increasing material use and embodied impacts, while stricter deflection limits reduced beam utilization and led to 9–12 % higher environmental impacts due to oversizing. Although higher reuse rates (RR) generally corresponded to lower impacts, some fully reclaimed (RR = 1) designs exhibited higher total environmental scores because of poor stock matching or excessive oversizing.
Transportation logistics emerged as a key determinant of reuse efficiency. When reclaimed steel was sourced up to 800 km farther than new steel (Δd = 800 km), its environmental advantage declined by over 30 %. Conversely, when reclaimed stock was locally available and new steel was transported longer distances (Δd = −800 km), reuse efficiency improved.
The reuse rate (RR), defined as the ratio of reclaimed weight to total frame weight, ranged from 0.14 to 1.0 across scenarios. The study also introduced a damaged reuse rate (DRR) to quantify the proportion of damaged reclaimed steel incorporated into designs and found that excluding these items could increase environmental impact by up to 46 %, particularly when new steel sources were distant.
Practical Applications for Enhancing Sustainable Practices
The proposed optimization framework has significant potential for advancing sustainable construction practices. By enabling the precise selection of reclaimed steel elements based on environmental impact, structural performance, and logistical constraints, it supports data-driven decision-making in building design. This approach allows for the integration of reclaimed materials into structural systems without compromising safety or functionality.
Practically, the framework can be applied to low-rise residential, commercial, and modular construction projects, promoting circular material flows and reducing dependence on virgin steel. This helps lower lifecycle emissions and overall environmental impact.
Although not part of the study itself, the researchers note that future implementations could be enhanced by digital technologies such as coded steel passports, digital twins, and artificial intelligence (AI) to improve traceability and quality assurance.
Conclusion and Future Directions
In summary, the proposed framework demonstrates a robust and effective approach to addressing the challenges of steel reuse in building construction. By integrating MILP with LCA and structural analysis, it provides a scalable method for minimizing environmental impacts while preserving design integrity. The study also stresses that environmental efficiency depends not only on maximizing reuse rates but also on stock quality, dimensional compatibility, logistics, and design flexibility.
Future work should extend the framework to incorporate dynamic stock databases, real-time logistics modeling, and diverse structural typologies. Regulatory mechanisms that facilitate the reuse of damaged, yet structurally sound, steel components are essential to realize the potential of reclaimed materials fully.
As the construction industry advances toward net-zero goals, such data-driven methodologies will play a pivotal role in promoting sustainable, resilient, and resource-efficient buildings.
Journal Reference
Mahdavipour, M, A., & et al. (2025). Optimized steel frame design using reclaimed steel: Logistics impact on reuse efficiency. Journal of Construction Steel Research, 236 (Part B), 110046. DOI: 10.1016/j.jcsr.2025.110046, https://www.sciencedirect.com/science/article/pii/S0143974X25007242
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