Multi-objective design optimization applied to the structural design of a bridge with reused elements and recycled concrete aggregates
C. Braendstrup 1, S.J. Wang 1, M.W.F. Vullings 1, S.L.A. Valcke 1, J. Lennartz 1, D.L. Allaix 1, S. Groenia 2, A.J. Bigaj-van Vliet 1
1 TNO, Delft, the Netherlands
2 University of Twente, the Netherlands
Sustainable design of concrete structures may contribute significantly to reaching the European Union's ambitious targets regarding climate change and circularity. However, a sustainable structural design must meet multiple performance criteria simultaneously, making the design process more complex. To navigate this complex design and decision process, multi-objective design optimization is proposed in literature. This paper demonstrates the application of multi-objective design optimization to structural design, using the design of a bridge with reclaimed concrete girders and recycled concrete aggregate (RCA) as case study. First, a parametric model is defined for the design of the structure, including the relevant parameters, boundary conditions, and calculation models on material and structural level. Next, five design objectives are selected to optimize for in the case study, which reflect economic, environmental and circularity aspects. A multitude of optimal design solutions within the solution space are then generated using multi-objective design optimization algorithms and visualized in parallel coordinate plots. The advantages of multi-objective optimization in structural design that are found, are twofold: (1) the multitude of optimal design solutions gives insight into all possible interdependencies between design variables and performance criteria (objectives) and (2) it enables transparent decision-making. Using the results of the case study, it is shown how trade-offs can be quantified and made visible to all stakeholders. Furthermore, this study shows how multi-objective design optimization can be used to determine realistic design requirements for use in tenders.
Key words: Concrete structures, structural design, multi-objective design optimization, sustainability, circularity, reuse, recycling