A Conceptual Framework for Enabling Structural Steel Reuse Utilizing Circular Economy in Modular Construction

Steel production is a major contributor to resource use and greenhouse gas emissions, accounting for nearly 8% of global CO 2 emissions, with structural steel accounting for more than half of this share. As the construction sector moves toward decarbonization, strategies for reuse, particularly within Modular and Offsite Construction (MOC), are receiving growing attention. This study presents a digitally integrated framework for the recovery, testing, and reuse of structural steel in MOC, grounded in Circular Economy (CE) principles. The framework is based on a systematic review of 162 academic, industry, and case study records and is structured across four stages: (1) material recovery, (2) testing and certification, (3) integration into MOC, and (4) performance evaluation. Building Information Modeling (BIM) and Material Passports (MPs) provide digital infrastructure for traceability, documentation, and compliance with established protocols, such as SCI P427 and P440. Reuse outcomes are assessed using the Modular Reuse Ratio (MRR), Carbon Savings (CS), Lifecycle Cost Savings (LCS), and a tailored Material Circularity Indicator (MCI). By aligning certification requirements with digital processes, the framework addresses current gaps in traceability, standardization, and decision support. It provides a scalable and replicable model that advances structural steel reuse, contributes to sector-wide decarbonization, and supports alignment with emerging CE and performance-based certification schemes.