Steel visions. Fiorini’s “mechanical architectures”

The contribution, through archive sources and bibliographic documentation, retraces the story of Fiorini’s work and especially his relationships with important architects and engineers of the time, rediscovering his influence on the Modern Movement and describing the important connection between “mechanical architectures” and attractive steel structures. In 1930s Guido Fiorini introduces for the first time a new kind of structure called “Tensistruttura”: a spatial system made out of tensioned membranes that, through a particular geometric arrangement and loads distribution, are suspended enhancing the tensile strenght of steel tie-rods. Fiorini describes his inventions as “mechanical architectures, that can only be built of steel, because of their articulation. They are composed of pivots, rollers and chains, so they are machines and they are the only comprehensible constructions for current machine civilization”. The engineer and architect, originally from Bologna, represents an atypical character of Italian architectural scene: the pragmatism of his designs probably comes from his close work with industries specialised in metal construction such as the Savigliano Company based in Turin, but at the same time he writes articles on precious architectural reviews like Casabella and he participates at the meetings of Futurism avant-garde which influences his ideas. The Piedmontese company is fundamental to carry out a detailed technological study about the project of Tensistruttura. Fiorini describes it as a “particular static arrangement, made of iron and steel, which uses tie-rods to unload, with a perfect balance, the weight of building floors on one or multiple cores, that are particularly proportioned to bear compression”. He chooses a clear strategy for his designs, that move towards a progressive discretization of the architectural organism: compression is supported by the central core, surrounding spans are arranged according to parallel directions, tie-rods are tensioned to support the slabs, each floor is independent so as to avoid the transmission of tensions between the slabs, the top of the building is organised as a step pyramid, walls are built of light materials that guarantee a dry construction. Fiorini senses that this technology of suspended structures, typical of bridges, can be used for ordinary buildings like houses, offices and commercial stores, but particularly for special buildings, indeed he develops models of innovative towers and hangars. Concerning the towers, his first version consists of a building that has cantilevered upper floors and the ground floor completely cleared. This original layout partially changes in next proposals in which are added some pilotis around the core to better support intermediate spans. Through the diffusion of Fiorini’s publications, these structural concepts are known also by Le Corbusier, Fiorini meets the Swiss French master in 1931 in the Colonial Exposition of Paris, convention for which he designs the futurist food pavilion “Ristoratore d’Italia”. Until 1936, between the two designers there is a continuous exchange of letters concerning in particular two aspects: the interest of Le Corbusier for the Tensistruttura, considering its potential advantages especially for his urban plans; the possibility to promote his professional activity also in Italy, keeping in touch with designers and politicians well known by Fiorini. Le Corbusier suggests the Italian designer possible improvements, correcting also construction details drawn by Fiorini and Savigliano Company, and adopts the Tensistruttura models in the second version of Algeri urban plan. About the hangars designed by the Italian architect, these are conceived as revolutionary objects that are able to show their monumental and tectonic nature: taking the project of Linate hangar as an example, structure becomes the key player of a construction subject to decomposition and optimisation of its components. In this project, that has a large influence on some works of Pier Luigi Nervi like Burgo Paper Mill, Fiorini renounces to follow artistic purposes transforming the structure “in the architecture of rational calculation, of brave audacity and simplicity”. The Fiorini’s influence can be also seen in the Le Corbusier’s “Pavillon des Temps Nouveaux” of International Exposition of Paris built in 1937, a “bold and flexible construction” that is similar to a tent, which shows different colours for each side and it is supported by a double system of tensioned cables. The dialogue and mutual suggestions between Fiorini and Le Corbusier are paradigmatic of the openness to the international debate of some Italian designers that, released from the regime dynamics, are able to bring architecture in foreign contexts marked by a greater cultural liveliness. It is not possible to define Fiorini’s influence on an important designer like Le Corbusier, but meetings and correspondence between them have been fundamental to develop their research activities thanks to mutual sharing of knowledge and intuitions. There are evidences of Fiorini’s influence on Italian architecture of the Second Half of the 20th century and some buildings prove the timeless quality of his “visions”. In the period of architectural utopias of ‘60s and ‘70s, the project of New York Helicoidal Skyscraper of Manfredi Nicoletti evokes the topics and, above all, structural and technological arrangement of Fiorini’s skyscrapers.