Design-Optimization Workflow for 3D Concrete Printing of Spanning Structures (2023-07)¶

The process of 3D concrete printing (3DCP) and early age material behaviour introduce design constraints related to overall form and toolpath design. These requirements are particularly acute in the case of spanning structures. To avoid printing failure and identify forms that are amenable for 3D printing, a workflow is proposed to optimize forms based on buildability constraints and user preferences. The workflow encompasses four steps: generation of an initial structure based on predefined parametric models and user input, generation of an appropriate toolpath, structural simulation in early and hardened states, and structural optimization of the form and toolpath considering buildability, serviceability, and printability constraints. The workflow was validated by designing and printing a 1.2-meter tall cross-vault. The optimization process focused on studying the scale effect, by comparing how the cross-vault design changes with the area to be enclosed; fabrication process, by evaluating how different construction processes influence the design; and structural performance vs printing quality. Results indicate higher slenderness for larger scale solutions, which is explained by the increased printing time per layer and thus material strength. Additionally, optimization results indicate that increasing printing time per layer through specific fabrication strategies led to material savings up to 50%, and is key to fabricate solutions that are slender, functional, and display better printing quality.