Structural Folding

Structural Folding for Architectural Design
A new approach to the design of folded plate structures in architecture

Pierluigi D’Acunto
A thesis submitted to attain the degree of DOCTOR OF SCIENCES of ETH ZURICH
2018

From an architectural standpoint, folding as a design operation enables the creation of forms that can deal with different requirements in terms of both space and programme. Moreover, from an engineering perspective, folding is an effective strategy to generate efficient structures that withstand the applied loads through their form.

Although these two aspects have been explored extensively as independent research questions, so far, only a few attempts have been made to define design methods that can take into account both spatial and structural opportunities of folding at the same time.

This research by Pierluigi D’Acunto presents a new approach to the design of folded plate structures in architecture. A design method that takes advantage of the interaction between the spatial and structural features of folding is proposed, which aims at merging architecture and engineering based on a holistic approach to design.

The proposed method is intended to assist the creation of folded plate structures since the initial phase of the design development and can be used by both architects and engineers. The method builds on a process that relies on the implementation of geometric operations in three dimensions. In particular, a statically rigid folded plate structure is defined within a kinematically stable reference grid.

While generating the structure, an architectural space is produced at the same time. Without compromising the topological properties of the folded plate structure, its form and the distribution of its internal forces can be adjusted by the designer to meet specific architectural and structural requirements. This goal is achieved by controlling the position of the nodes of the reference grid while abiding by a series of designer-defined geometric constraints.

Grounded on 3D graphic statics and the theory of plasticity, a specific strut-and-tie model for folded plate structures is introduced as the structural basis for the design method. In this model, the internal forces are transferred via linear members both along the folded edges and within the folded plates.

Based on the strut-and-tie model, in-plane stress fields in the folded plates can be derived. The applicability of the proposed approach is facilitated by the implementation of the design method into a parametric digital toolkit, which can be employed to create folded plate structures at various scales. The potential of the method in real design scenarios is demonstrated through a series of experimental designs as case studies, including full-scale prototypes.

Credits for pictures used in this thesis: Wester 1984, Buri 2010, Samuelsson and Vestlund 2015, Ingold and D’Acunto of 2017