Il tubo Innocenti e il “Sistema Nervi”: la realizzazione artigianale delle grandi coperture in ferrocemento

On Febraury 1934 Ferdinando Innocenti patented an original “device for uniting tubes of metallic structures”, a steel coupler producing the friction to clamp two perpendicular steel tubes, forming versatile scaffolding and scaffolding. The efficiency was so evident that, in those years, even Pier Luigi Nervi decided to combine his ideas with the Innocenti tube and coupler. In the Air Force Angar of Orvieto and Orbetello, the Innocenti scaffolding became part of the invention of structural prefabrication. The scaffolding easy to assemble/disassemble and reusable support, in terms of cost and time, the idea of the construction of large roof, by combining, small on-site prefabricated pieces. In the aftermath of WWII, the Innocenti scaffolding support the first application of the Nervi System for the spectacular roofing of Salone B in Turin. A huge movable scaffold, supported the set up of the 144 light waves in “ferroconcrete” composing the vault: each arch is made up of 13 wave segments that, only 3,8 cm thick, can be easily mounted on a spectacular movable Innocenti castle. The combination of the two systems allows the conclusion of the time in just 80 days. In 1956, for the construction of the “Palazzetto dello Sport”, the tube-coupler” was included in the overall price of the dome as an essential component of the “Sistema Nervi” and in 1958, in the monumental building site of the “Palazzo dello Sport”, it was used, alongside the traditional timber framing, for the set up of the prefabricated pieces in “ferroconcrete”. So the two Olympic domes were composed on exoskeletons of metallic tubes: their image, widely diffused by the international press, establishing itself as an icon of the Italian artisanal construction site.