Natural and Lightweight Structures

Image: BIC chart of structural performance, Institute for Lightweightstructures, Stuttgart (IL21)

Natural Models

Frei Otto, Germany 1972

Frei Otto was an architect and structural engineer who made significant contributions to the research, development and construction of lightweight structures. He began his work on lightweight structures during WWII at a prisoner war camp in Chartres, by creating lightweight tent structures for shelter with the minimal amount of material available. This was one of the first and many uses to which he applied lightweight structures. He was particularly interested in the economical and ecological performance of these structures.

Throughout his career Otto built complex physical models to test and optimize the performance of form-active structures, often tensile structures, but also shells and arching systems. Even though he had access to structural analysis software for many of his projects, the calculations of the structural geometry were generally derived from these form-finding models, which acted as physical computation machines. The iterative process of this form finding and optimization method is one of the four main aspects we consider in Frei Otto’s legacy; together with his studies of Natural Structures, his built work (for which he often acted as the structural engineer, rather than the architect), and his fundamental research of structure system classifications (see Taxonomies).

In the 1960s Otto developed various forms of structure systems categorizations at The Institute for Lightweight Structures in Stuttgart. Some of these systems were conceived as schematic diagrams that address relations between structures in nature, art and engineering. Other classifications define and put in relation highly specific parameters of structures, including load cases, form, material and modes of redirecting forces. His most rigorous and detailed explorations map and compare the performance of various structures - engineered and ‘natural’ - and establish an “economical” principle. He invents a new physical performance unit, the Bic, that puts an object’s mass and structural capacity in relation. In intricate charts and drawings various structures are mapped meticulously along Bic parameters. Characteristically, they all consist of living and nonliving, natural and engineered structure, and none of them claim to chart a complete set of structures or enclosed systems.

Otto founded several institutes dedicated to the research and experimentation of lightweight structures such as the Institute for Lightweight Structures and the Special Research Unit 230 in Stuttgart. He was always interested in open and multidisciplinary collaborations, and it was in the “Biology and Building Research Group” at the Technical University of Berlin that he practiced his research along with biologists and microscopists (J.G. Helmcke et al.). Together with architects and structural engineers they applied systems of analysis for tents, grid shells, and other form-active structures to understand the performance of biological structures and forms. Otto defined as “Adaptable Architecture” those structures that allow changes within their physical lifetime. He also defined the optimization of used material and built mass as the “Lightweight Principle”.

Figure 6 - 8: Classification of Structures, Institute for Lightweight structures, Stuttgart (IL21) According to Otto, the building structures that we have been occupying for ten thousand years are still not entirely understood, nor were they put in relation. His matrices of principal systems and applied structures have open cells, which distinguishes them from other ‘completed’ classification systems and thus invite to fill in blank spots. We identify spots for nano-structures (subvisibilia) and extraterrestrial structures within the taxonomy. Otto’s work on natural constructions is part of a rational form-finding process following natural laws, and is also part of a larger vision directed at a peaceful and free society that exists in harmony with nature.

Suggested readings:

Frei Otto, Bodo Rasch: Finding Form: Towards an Architecture of the Minimal, 1996, ISBN 3930698668

Philip Drew, “Frei Otto; Form and Structure”, 1976, ISBN 0258970537, ISBN 978-0258970539

Philip Drew, “Tensile Architecture”, 1979, ISBN 025897012X, ISBN 978-0258970126

Nicholas GoldsmithThe physical modeling legacy of Frei Otto First Published May 4, 2016 Research Article, https://doi.org/10.1177/0266351116642071

Möller, Eberhard. Nungesser, Hans. Adaptable Architecture by Frei Otto – a case study on the future viability of his visions and some forward ideas. Proceedings of IASS Annual Symposia, IASS 2015 Amsterdam Symposium: Future Visions – Historical Spatial Structures, pp. 1-12(12). International Association for Shell and Spatial Structures (IASS)

Figure 1 (top): Mannheim Multihalle, 1975 Figure 2 (middle): Olympic Stadium, Munich, 1972 Figure 3 (bottom): Physical computation model for Munich Olympic Stadium

Figure 4 - 5: Natural Structures, Special Research Unit 230 (SFB 230), Jean-Marie Delarue ‘Minimal Folding’ configurations’

Figure 6 - 8: Classification of Structures, Institute for Lightweight structures, Stuttgart (IL21)

Figure 9: BIC chart of structural performance, Institute for Lightweightstructures, Stuttgart (IL21)