BAYA algorithm : characterization of the behaviour of braided structural shells

The use of naturel fibers dates back at least to the Neolithic period. People around the world have employed braiding techniques and basketry craft to design a large panel of objects, clothes, furniture, boats, etc. In the field of construction, we can witness the use of braided natural fibers in numerous vernacular shelters, but they are generally limited to non-structural filling elements. The lack of description of the braided structures behavior in the literature is underlying that these kinds of techniques were not commonly used for a structural purpose. The aim of our research is to demonstrate the feasibility of designing and building structural wicker braided shells for architectural purposes, and to provide designers with the necessary tools for this process. Thanks to the theoretical and experimental study of a braided specimen at a local scale, we defined the relation between density and orientation of the stems and the fields of principal stresses on an idealized continuous loaded surface : "each field of stress is related to an optimal braiding". These data are filling an algorithm, BAYA, making design and optimization of braided shells accessible and easy to use for architects and practitioners. This innovative research is demonstrated by the realization of full-scale benches with a load capacity of about 100kg during a scientific challenge event organized by the École des Ponts ParisTech in 2023 and 2024.