Special IASS 2024_Baya Project: Building Structural Shells in Wicker

Abstract

The growing of natural fibres – such as wicker – is deeply virtuous: it helps to diversify the forest cover, it requires limited inputs – even in water, little maintenance, and its CO2 emissions are minimal. Their uses in basketry date back to the Neolithic period, and even probably before. People around the world have employed braiding technics and basketry craft to design a large panel of objects, clothes, furniture, boats, etc. In the field of architecture and construction, we can identify natural fibre uses in numerous of vernacular shelters, but they are generally limited to non-structural filling elements. The scarcity of mechanical characterization of wicker material in the literature is underlying that, since now, these kinds of materials are not commonly used to a structural purpose.The aim of our research is to demonstrate the feasibility to design and build structural wicker braided shells for architectural purposes, and to provide designers with the necessary tools for this process. Thanks to wicker mechanical characterization and to experimental measurements, we developed a law which defines a relation between density and orientation of the stems and the fields of principal stresses on an idealized continuous surface: “each field of stress is related to an optimal braiding”. These data have supplied an algorithm, BAYA, making design and optimization of braided shells accessible and easy to use for architects and practitioners. Even if our research focused on wicker, it should be easily adaptable to other fibres and plants as, for instance, rattan or reed. This innovative research is demonstrated by the realization of a full-scale public pavilion hanging from trees on the belvedere of the Butte du Chapeau Rouge park (Paris XIX), and a 12.8-meter-long footbridge for the Utopies Constructives festival in Richelieu’s Park.