© ETH Zurich / Arup

Structural folding

Structural folding has been gaining prominence in recent years. Folding represents a powerful, consistent technique to integrate architectural and structural thinking within the design process. It enable the design and the production of efficient structures capable of resisting external applied loads through their form rather than by accumulation of material. Folding can be viewed as a way to effectively integrate architectural intention and engineering thinking towards a holistic approach to design.

This joint research project on structural folding between Arup and ETH in Zürich is founded on integration of the disciplines of engineering and architecture. It focuses on the diverse role of folded forms, which act as mediators between load-bearing capacity and architectural ideas. The aim of the project was to provide engineers and designers with insights and information on the practical application of structural folding, and to provide guidance on the use of a newly-developed parametric digital toolkit for structural folding at building scale.  This approach can enable full advantage to be taken of the direct relationship between the spatial and the structural potential of folding.

The collaboration between Arup and ETH Zürich has led to the development of a parametric digital tool to facilitate the integration of structural folding in architecture. The tool has been developed around a structural model for folding based on plasticity theory and the method of graphic statics.

The parametric digital tool operates in a three-dimensional digital environment.  It allows evaluation of the internal forces within in a folded structure under certain loading conditions.  The tool offers a rigorous yet flexible means of generating and evaluating design options throughout the design process.  It gives the user the capacity to modify input geometry or boundary conditions while receiving real-time feedback on the structural implications of that design choice.

Using the parametric digital tool, a full-scale prototype called foldKITE in the form of a suspended folding pavilion was designed and built for exhibition at the IASS International Expo 2015. The foldKITE pavilion explored the potential of folding in the field of ultra-lightweight structures. Using the parametric digital tool, a strategy was implemented to control the amount of folds in the folded surface so as to distribute mass in space and to adjust the internal forces in order to reach the static balance of the system. The process of digital fabrication of foldKITE was integrated into the design with a file-to-factory digital workflow.

The development of a structural folded design necessitates that architectural and engineering aspects are addressed together, starting from the earliest conceptual phases of the design process.  Designing with folding fosters continuous cooperation between architects and structural engineers and in this way suggests an alternative to the hierarchical and sequential interaction that is the conventional approach to design. By doing so, it contributes to design process efficiency.

By using geometrical operations only and by adopting the use of graphic statics, the design method is generally material- and scale-independent.  This allows the same strategy to be applied to various design scenarios.