PSI - Issue 84

Fabio Brancaleoni et al. / Procedia Structural Integrity 84 (2026) 1095–1102

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is subsequently treated, with the progressive understanding of their behaviour in the most stressed portion, i.e. the saddles, where local effects are significant and complex. 2. The Pioneers, First Half of the XIX Century Significant attention was given since the beginning of the century to iron wires, wrought or drawn, though initially considered less durable and reliable with respect to the chains (Drewry, 1832). After numerous small-scale samples, the first constructed was in the United States, with a modest suspended footbridge built in Pennsylvania by Josiah White and Erskine Hazard in 1817 over the Schuylkill River, followed by a few in UK (Bender, 1872). Though, the development of bridges with wire cables was not to occur where the first ones were built: it was in France that the technology expanded, primarily with the figure of Marc Seguin (Seguin, 1824), credited with numerous works, all very similar and of spans less than 100 m. For the cables of such bridges, a fundamental problem was the installation which, albeit with many variations, was carried out by assembling the wires on ground along their entire length and then hauling them into position using capstan winches and connecting them to shorter sections already placed at the tower tops. This imposed a strong limitation on the achievable spans: for real progress, a different technology was needed, which was devised in France by Louis Joseph Vicat (Vicat, 1834), with a method of assembling cables made entirely on site: thus the technology of “aerial spinning” was born (Gimsing, 2012), and the way was opened to much greater spans. The first with this nouvelle manière de confectionner les càbles en fil de fer was in Switzerland and set a record: the bridge over the Sarine in Fribourg, with a span of 273 m, built in 1834, with Joseph Chaley as the main designer. Other bridges followed but, once again, the technology flourished elsewhere: back in the United States. 3. The Great “ American Century”, from half XIX to half XX In the United States of the nineteenth century, all the conditions for the development of large bridges were present: expanding industry, untouched territories and large rivers or straits. The two figures considered here are Charles Ellet Jr. (Kemp, 1999) and Johann Augustus Roebling (Haw, 2020). Ellet, born into a well-established American family, studied in the United States and furthered his education in Europe. Upon returning home, he made several proposals for suspension bridges, built his first one over the Schuylkill at Fairmount in 1842 and wrote a popular text (Ellet, 1847). In 1848, two major opportunities arose for him: a railway suspension bridge over Niagara Falls and a bridge over the Ohio river at Wheeling, a new record with its 308 meters span. Both, however, met unfortunate fates: construction of the first began but was halted by financial and political problems, while the second was destroyed by a storm in 1854 (Kemp, 1999), to be rebuilt and reinforced several times, altering its original design (Cuddy, 1999). Ellet later died in 1862 from wounds sustained in the Civil War, but his unlucky figure gave an important impetus to American suspension bridges. Roebling’s origins were quite different: born in Prussia, the son of a shopkeeper, he studied in his homeland where he found no outlet for his ideas in a society he considered rigid and stagnant. He emigrated to the United States and, leaving aside many aspects and other activities connected to his unique personality, he always had a passion for suspension bridges. His first opportunity came with a suspended aqueduct over the Allegheny in 1844, followed by three more. In 1846, he built the first true suspension bridge over the Monongahela River, with eight spans of 57 metres each. In opposition to Ellet, the emerging Roebling developed his own structural concept, which featured stiffer decks and stays, improvements in aerial spinning techniques and in the splicing and anchorages for the wires (Hildenbrand, 1877). His first major work was born from the ashes of one of Ellet’s projects: in 1855, he successfully resumed the project for the railway bridge over Niagara Falls. Having achieved solid fame, in 1867 he set his first record with the Cincinnati-Covington Bridge over the Ohio, with a span of 322 metres, and devoted himself to designing what would become a symbol: the iconic Brooklyn Bridge over the East River in New York. However, Roebling was never to see it: he died in 1869 because of an accident during a site inspection, with the bridge completed by his son Washington Augustus, an excellent and equally unfortunate engineer (Wagner, 2017), assisted after a serious accident that left him in poor health by his wife Emily Warren Roebling (Weigold, 2019). The Brooklyn Bridge was a record in many respects, primarily the 486 m span, and with it the technology made a huge leap forward, laying the foundations for the development of great American bridges (Petroski, 1996), with main works and figures comprising Othmar Hermann Amman, his the two records of the Washington and Verrazano Narrows bridges, Joseph Baermann Strauss with the Golden Gate, David Barnard Steinman with the “Mighty Mac” Mackinac,