Il tempo del “tubo-giunto” Innocenti

How were realized the reinforced concrete works of Italian structural art in the dimension of the handcrafted construction site? The construction process of the arch bridges of the Autosole or the Pier Luigi Nervi’s Palasport domes based its challenge on a unique construction tool: the Innocenti tubular scaffolding. Deus ex machina of this revolutionary construction tool was Ferdinando Innocenti, a blacksmith who, grew up in the paternal laboratory, patented in 1934 a revolutionary “device for uniting tubes of metallic structures”, consisting of a clamping bolt with a T-shape head and a hinge. Of rapid assembly, portable, reusable and much more cost-effective than traditional timber framing,the system immediately established itself on the national building and still outstands among the steel products manufactured in Italy. In the Thirties, it was applied to reinforced concrete construction projects, to set up imposing, temporary works to suit the needs for Fascist propaganda, and also for military use. In post-war years, following the establishment of a new company (Ponteggi Tubolari Dalmine Innocenti) founded by a team of structural engineers, the system was used in the construction of aweinspiring, dismountable and portable steel tube scaffolds designed to support viaducts connecting the new motorways. In 1958, the transfer of the scaffold to be applied to the construction of the twin arch bridge across the Aglio river along the Autostrada del Sole was a pioneering technology performance. During the same months, even Pier Luigi Nervi used the pipe joint system to combine the precast and cast-in place components of his Palasport domes. In the 60’s, as the system had risen fast on international scene, construction gradually turned to more standardised solutions. Between 1961 and 1963, the pipe joint system was used in the construction of the last arch bridges connecting the Autostrada del Sole in the Florence-Rome. That anticipated also the end of the cast-in place, reinforced concrete arch era and the dissolution of the distinguishing features of the Italian construction site that had been represented by Ferdinando Innocenti’s creation