Additive manufacturing (AM) has expanded possibilities for materialising structures that achieve their strength through intelligent, but complex geometries. However, conventional AM techniques, such as thermoplastic-based fused deposition modelling (FDM), also rely on material with weak strength and stiffness properties, which limit their full-scale building construction applications. This paper articulates one of several novel design-fabrication strategies responding to this challenge jointly developed by MIT, ETHZ and Tongji researchers in a recent workshop—strategies optimising FDM as a technique for producing self-supporting structural scaffold that can be printed flat and bent in-place on site, and whose strength is built up gradually by additional application of structural material layers. The approach leverages computation to synthesise the advantages of traditional and additive manufacturing: force-explicit equilibrium-based design methods are used to derive complex doubly-curved and compression-only forms that respect the limits of the scaffolding material, and can be digitally fabricated and assembled into durable structures without intensive labour and formwork requirements.
Inspired by principles of shallow arching action, this paper—part 2 in the series—develops an AM-enabled multi-phased construction method for creating a walkable full-span structure capable of accommodating live structural loads. Specifically, the novel technique approximates a shallow compression-only geometry in a series of folded AM-produced scaffold panels to create a corrugated profile with increased structural depth, which augments the shell’s structural stiffness to support an initial layer of incrementally applied concrete. The corrugated concrete in turn supports a final layer of concrete continuously filling the corrugated space to create a robust system of structural stiffeners and diaphragm. An integrated form-finding method was devised within the COMPAS computational design framework to simultaneously optimise the variation in the shell’s corrugation depth, and in the density of its internal discretisation as printable filament infill patterns—while incorporating fabrication and assembly considerations, and the print material’s properties. The feasibility of the novel assembly process is demonstrated with the construction of a bridge measuring 5-metre in span. The produced prototype illustrates one alternative design-fabrication framework synthesising digital and traditional fabrication techniques through smart structural computation, in order to open new possibilities for materialising geometrically complex, live-load-bearing and moderate-span concrete structures with minimal formwork.