Symbol and technique of steel domes in Italy

This discussion is a reflection on the development of the domes in Italy as a result of the metal structure where you can identify three distinct phases. The revolution of the metal cover began in the nineteenth century, when the middle class chose the dome, symbol of ecclesiastical power and secular government, to mark the spaces called to represent the social and economic prestige achieved: the store galleries and theaters. The formal apparatus which was used for the construction of this new type of coverage, in the era of Neo-Renaissance revival, was clearly derived from classical models; however, they renewed the traditional aspect with the introduction of a new structure, which made the transparency and lightness of the distinctive characteristics of its image. A formal apparatus accepted by mainstream architectural era, was used together with a technological system that was innovative and introducing revolutionary techniques. Therefore metal construction represented for the dome typology a turning point with revolutionary characters: iron structure not only introduced new technological devices and new constructive techniques, but it involved a deep effect on the image of the massive domed structure, that gradually became a light and transparent element, able to establish the transition between Heaven and Earth. The architecture of the 19th century introduced new functional models, as urban galleries and markets, or defined the renewal of traditional typologies, as the historical theater, describing an interesting field for the experimentation of new materials and techniques addressed to a new aesthetic. The "Modernity" of this period was also marked by ambiguity and contradictions, like immanentism, historicism, and others languages, but two opposite positions were recognizable: the formalism of the academy and the technological research of engineers. The galleries in Naples and Milan and Palermo Politeama theater were the most significant episodes of metal domes made in the Risorgimento age. The new technology acquired and the new possibilities offered by industrial progress could have ensured a large fortune to the theme of the big metal cover, where the cultural and social conditions had not stopped the research in this area. The first half of the 20th century was marked by a decrease of metal structure use, caused by different reasons, like the autarchy period, the commitment of Italian industries for the two wars and changes in the cultural context. All these aspects fostered the return to traditional technologies affecting also construction of domes, even though in this period some examples of interesting architectures demonstrated that the feeling of experimentation wasn’t completely lost by a few designers, such as in the case of Adalberto Libera and Raffaele De Vico who respectively designed the dome of Palazzo dei Congressi and a a geodesic dome to host a new aviary, both in Rome. Only after World War II, a period that represented the next phase of this development, the debate on the metal became quite important. In particular, the research ranged from the solution of the shell of the large assembly spaces such as sports arenas, to the complete redefinition of the envelope. In this period new theoretical and technological models came from experiments of internationally acclaimed architects and engineers who explored the potentialities offered from steel to cover large spans: new assembly and production techniques of steel components, proposed by Konrad Wachsmann; studies about truss structures, shown in Buckminster Fuller’s fundamental researches about geodesic systems; application of tensile structures, as in Frei Otto’s works. Furthermore these international contributions were important as the experiences acquired by important figures such as Pier Luigi Nervi, who used the dome as a global envelope, made of contemporary technologies and construction techniques, and exploring unusual static schemes that led to a definition of new geometries. The new steel domes were described by the geometry of the revolution, but architects added to the semicircular or semi-parabolic generating section, the low arc and the polycentric section. This change was formally implemented through the establishment of a technological device and new technical know-how. If in the nineteenth-century structural elements were in cast iron, with traditional static models, the desire to exploit the properties of steel and enhance the tensile behavior led to the definition of innovative systems resistant. These experiences produced significant episodes, such as the Sironi’s sports hall in Genoa, the Piano’s Bubbles on the port of Genoa and the museum at the Lingotto in Turin. The dome of the third generation exceeds the Euclidean geometry and is no longer described by the revolution of a section around an axis as it exploits the possibilities introduced by the numerical control machines. This new generation is not yet a well-known fact in Italy but it is a field of experimentation for some contemporary Italian architects. The modular design gradually disappears and the help of the computer enables you to define a schedule of distinct elements which, together, allow the assembly of complex structures. Recent projects of Massimiliano Fuksas show this innovative way, which suggests a new era for domes taking, in other forms, new variations from ancient roots.