Optimizing Structural Grids in Concrete Buildings: A BIM-Based Multi-Objective Assessment of Cost and Embodied Carbon

Document Type

Article

Publication Date

2025

Abstract

Reducing embodied carbon in concrete buildings is increasingly critical as operational emissions fall, yet early structural-grid decisions are typically driven by cost with limited carbon visibility. This study evaluates how grid spacing influences both embodied carbon and cost in a low-rise reinforced-concrete frame and proposes a practical early-stage assessment workflow. A BIM-based model set was developed to represent six published grid layouts ranging from dense short spans to wide long spans. For each alternative, structural quantities were obtained from the BIM model and used to estimate embodied carbon and a comparative cost proxy. Embodied carbon was assessed using a consistent factor set and EN 15978 life-cycle modules covering product and transport stages and end-of-life. Cost performance was compared via a normalized structural material-cost index, with a unit-rate sensitivity check. Results show a clear trade-off between concrete volume and reinforcement intensity: wider spans reduced concrete demand but increased reinforcement per unit area. Dense grids required the most material and produced the highest embodied carbon and cost. The widest grid achieved the lowest total embodied carbon, while a medium-span grid minimized cost, demonstrating that the economic and environmental optima do not coincide. Across the six alternatives, grid selection reduced embodied carbon by up to ~48% and lowered structural material cost by roughly 50% relative to the densest baseline. The workflow enables rapid, transparent trade-off screening at concept design and can be extended to other building types, materials, and automated multi-objective optimization.

Comments

special issue of Journal of Engineering Science, ISSN: 1687 0530

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