Historical notes on the development of reinforced concrete

Historical notes on the development of reinforced concrete

Ugo Carughi (ICOMOS Italia)

Born in Europe in the second half of the nineteenth century on the principle of collaboration between iron and concrete, reinforced concrete was initially used for works of a mainly infrastructural nature.
The patents of the new construction system, from that of the lawyer J.C. Lambot (1855), who made a reinforced concrete boat in 1848, to that of the gardener Joseph Monier (1867), filed in Italy in 1883, and that of François Hennebique in 1892, led to the construction of the first reinforced concrete bridge in Wiggen, Switzerland, by Hennebique himself in 1894.
The new technology spread to countries where labor was less expensive and specialized, such as Spain, Latin America and Italy, where there was great availability of raw materials. In the early '30s of the twentieth century there were many bridges built in Italy with the new technology. From the pioneering one over the Tagliamento between Pinzano and Ragogna with three parabolic arches, each 49 metres wide (1903-1906), to the Risorgimento bridge over the Tiber in Rome, the most daring in the world for many years, with a single low arch of 100 metres span and 10 metres arrow (1909-1911), built by Porcheddu to his and Hennebique's design.

In Italy the Hennebique patent spread through the work of some agents, designers and manufacturers (Giovanni Antonio Porcheddu for Northern Italy, Attilio Muggia for Central Italy). The new technology was developed through the activity of important companies, such as the Alzano Sopra factory founded by Cesare Pesenti in 1884, or Ferrobeton founded in 1908 in Genoa. Reinforced concrete became part of the curricula of Universities and Engineering Schools thanks to first-rate personalities such as Muggia himself, teacher of Pier Luigi Nervi, or Arturo Danusso, who had trained in the Porcheddu company. But, above all, it spread throughout the world with extraordinary rapidity thanks to the economic and technological advantages and to the entrepreneurial initiatives of Hennebique himself who, starting from 1897 in Paris, organized annual congresses between his agents and dealers. The former concluded contracts in the countries where they operated; the latter had the concession to use the patent. From 1892 to 1908 the organization, which had grown to 42 agents, operated on all continents. Between 1892 and 1902, 7025 projects worth 120,000,000 francs were carried out. Theoretical studies also continued from the end of the 19th century. In 1886 Köenen used empirical formulae on beams from the Monier system; in 1894 Coignet and De Tedesco presented a method for calculating deflected beams based on Navier's hypothesis; in 1899 Paul Christophe presented the first text on systems for calculating reinforced concrete, taken from the German instructions of 1904 and the French Regulations of 1906; in 1899 Durand, Considere and others demonstrated the adherence between iron and concrete; 1904 saw the publication of the German Instructions on Reinforced Concrete Constructions and in Italy the "Prescriptions to be followed in the design and execution of ferro-concrete works". In 1907 they will be adopted by the Ministry of Public Works. In 1909 the "New standards for reinforced concrete constructions" were issued by the Swiss Commission for Reinforced Concrete. In 1911 new standards were issued in England by the "Joint Committee on reinforced concrete".

The contribution of Italian engineering up to the 1970s deserves a special mention. Among Pier Luigi Nervi's works are the hangars of Orvieto, Orbetello and Torre del Lago (1935-1942), the exhibition halls 'B' and 'C' of the Torino Esposizioni complex(1947-1950), the Olympic works in Rome(1956-1960), the Papal Audience Hall in the Vatican City (1966-1971). Also Riccardo Morandi's viaducts, among his other works, deserve special mention. Here are some of them which, in re-proposing the specific type with stays, represent, on a world level, a significant contribution not only from a technological point of view, but also from an expressive point of view. These include the Maracaibo Bridge in Venezuela (1962), the Polcevera Bridge in Genoa (1967), the Magliana Bridge in Rome (1967), the Wadi el Kuf Bridge in Libya (1971), the Pumarejo Bridge in Colombia (1974) and the Carpineto Bridge near Potenza (1978). Moreover we want to mention Silvano Zorzi's viaducts, in particular the bridge over the Po River on the Autostrada del Sole (1958), the viaduct over the Fichera stream on the Palermo-Catania motorway (1970-72), the so-called Viadotto dei Parchi in Milan (1970) and the extremely elegant viaducts over the Gorsexio stream (1973-78) and the Teccio stream (1973-76); the works of Sergio Musmeci, among which we must mention the viaduct over the Basento near Potenza (1975) etc. These are works linked by design methodologies inseparable from the technological and construction aspects, which make them fully historicized in function of a conscious recognition of cultural interest.