Pier Luigi Nervi’s Designing Tools: Geometry and Calculation in Structural Analysis

Extraordinary architect, professor, contractor and entrepreneur, Pier Luigi Nervi (1891 - 1979) was one of the protagonists of 20th century architecture and engineering. He experimented with the construction possibilities offered by reinforced concrete and was celebrated worldwide. A key factor of his success was his capacity to invent new shapes and new ways to build them, through an original method that combined two elements of his own invention: “structural prefabrication” and “ferro-cement”. The calculating method used as one of the main tools within this design process has been an unexplored field of research so far. An interesting case study is the Manifattura Tabacchi (Tobacco Factory) in Bologna, designed by Nervi after World War II and built between 1949 and 1964. During his career, Nervi designed many industrial buildings, combining functional and structural needs into aesthetically surprising forms. The Manifattura is known for its poured-in-place concrete slab system, using Nervi’s patented system of ferrocemento formwork to produce visually expressive slabs for the high-rise portion of the factory, and shell construction for the warehouse. The research on this building, led by a team of the University of Bologna together with Iowa State University, has focused on its history, on the analysis of its structural systems and on the relationship between process and production. Within this research, the analysis of the original calculation reports written by Nervi clearly shows his design approach, which develops from his pivotal academic education in the University of Bologna. Nervi graduates in Civil Engineering in 1913 at the School of Engineering of Bologna. In particular, two professors played a key role in Pier Luigi Nervi’s academic education: Silvio Canevazzi (1852-1918), professor of Structural Mechanics and Attilio Muggia (1860-1936), professor of Construction Technology. Led by Canevazzi, Nervi learns the importance of critical thinking applied to structural calculation, which is not a mere reproduction of numbers and equations, but a keen use of what the professor himself used to define as «tools» and «solutions». Placing critical thinking before calculations is the main lesson which Nervi learns in Bologna – a lesson which has developed within this School across the decades until the teachings of Piero Pozzati (1922-2015). In his calculation reports, Pier Luigi Nervi shows that at the core of every structural system there has to be a theoretical thought, which is the direct proof of the existence of each static solution. Numbers become a tool to verify design solutions, whose working principles are known by Nervi thanks to his deep static intuition. Moreover, this investigation has shed light on Nervi’s personal notes, sometimes almost didactic: in fact, he uses them as tools to describe his design process. Geometry and Structural Mechanics take priority over iterative calculations and define themselves as Nervi’s main tools. The case study of Nervi’s calculation reports written for the Manifattura Tabacchi not only represents a valuable contribution for the structural analysis of these buildings, but also offers a new interpretation on his designing tools.