A significant portion of the environmental impact of a building’s superstructure lies in its structural flooring. By leveraging funicular forms such as thin concrete shells, a materially and carbon-efficient alternative to bending-active flooring systems can be attained. In addition, through segmentation and the use of dry jointed interfaces, a segmented concrete shell allows for ease of disassembly compatible with circular economy principles for the built environment. This paper presents a novel segmented concrete shell flooring system that leverages the symmetry of revolution of the classical fan vault form to facilitate future design flexibility through increased reconfigurability. The design and form-finding of the segmented fan concrete shell are detailed through the use of an evolutionary algorithm and finite element analysis. Quarter-scale prototypes were digitally fabricated using a robotic concrete spraying process which were then assembled and tested to assess its structural potential, evaluate the limitations, and identify areas of future work. An embodied carbon analysis demonstrates that the system provides a mass and embodied carbon saving compared to conventional flooring systems while adding approximately a 20% embodied carbon premium over a comparable non-reconfigurable segmented shell flooring system. Rephrased, the proposed system provides a positive embodied carbon saving if enabling design flexibility through reconfiguration increases the life-span of the system by at least 20%. Through this work, it is shown that a segmented fan concrete shell presents a viable lightweight and carbon-efficient flooring system which has the potential to become a sustainable alternative that enables disassembly, reuse, and even reconfigurability for circular construction provided further research and development to address its current limitations for adoption in industry practices.

The Automating Concrete Construction (ACORN) project explored digital workflows from the design to the construction of reinforced concrete building floor elements, reducing carbon emissions and increasing efficiency of building processes. The resulting digital tool, named SQUIRREL, enabled the design of shells, composed of prefabricated segments, through an interactive framework, composed of parametric design tools, and informed by architectural, structural, and construction requirements, including building integration, fabrication, transport, assembly, and resource reuse. This paper presents the design and implementation of the SQUIRREL tool, focusing on the main design tasks for a segmented reinforced concrete shell, including formfinding and segmentation layout definition. This paper also documents the development and application of a Design Space Visualisation module within SQUIRREL, which streamlined parametric studies used to inform the design decisions behind the modelling and implementation process. Finally, we discuss the right balance between design automation and user interaction, which should inform the development of future construction-aware computational design tools.