chain bridges
But history says that where the modern suspension bridge was born was in America. A judge and inventor, James Finley, came up with the idea of a wrought-iron chain-suspended bridge. The Jacob's Creek Bridge was completed in 1802 in Westmoreland County, Pennsylvania, in western Pennsylvania. braces Finley, given the success of this formula that allowed a bridge to be erected at low costs and easy to build, presented a patent for his design in 1808, and published it in the Philadelphia newspaper, The Port Folio, in 1810. But the use of these bridges soon revealed the problem of oscillation: the bridge easily went into resonance, and the pressure exerted on the chains made them give way. In reality, America's experience in wrought iron engineering and quality was unreliable. The development of bridges was limited in size and load and many accidents interrupted the nascent success of the suspension bridge, since the breakage of a single link meant the breakage of the tensioner.
The technique soon crossed the Atlantic to find new followers among the British, who had an important development in metallurgy. The chains were considerably improved and the suspension bridges became very ambitious. The first British bridges were built around 1815 and their dimensions continued to grow: the Dryburgh Abbey Bridge (1817), 137 m, and the Union Bridge (Tweed) (not yet written) (1820). sailing ships and was "the first important modern suspension bridge."[11] It was at the time the largest bridge in the world, as most bridges of the time spanned between 70 and 100 m. Other notable bridges were the Conwy Bridge (1826), in northern Wales, and the first Hammersmith Bridge (1827), in west London. The Clifton Suspension Bridge (designed 1831, completed. in 1864 with a central span of 214 m) is one of the longest of the parabolic chain type arch. lights, and became a monument to the glory of progress in the midst of the European industrial revolution.
It was precisely its European development that exported the suspension bridge to the continental part. In France, the technology became known thanks to the apology expressed in British newspapers. A mission to study "Ponts et Chaussées" was carried out in 1821, without success). bollards according to proven methods. The Seguin Frères company (Annonay, Ardèche), led by Marc Seguin, proposed in 1822 an innovative project: the Tournon suspension bridge. The company quickly understood that a conventional suspension bridge was not possible in France due to the poor quality of the chains. That was the birth of cable. After several tests and a refusal from Ponts et Chaussées, the project was finally accepted. Added to the innovation of the cables was the use of hydraulic concrete for the foundations, of reinforced concrete (25 years before the first patent) for the superstructures and of reinforcing elements that stiffen the wooden deck. The suspension bridge took its modern form.
• - «View of the Chain Bridge invented by James Finley Esq.» [View of the Chain Bridge invented by James Finley Esqr.] (1810), engraving by William Strickland, published in an article in the Philadelphia and New York newspaper, The Port Folio, in June 1810.
• - An early proposal for the chain bridge over the Menai Strait near Bangor, Wales, completed in 1826.
• - In the background, Menai suspension bridge (Thomas Telford, 1826). In the foreground, the Britannia tubular bridge (Robert Stephenson, 1850). View ca. 1850.
• - Gray&action=edit&redlink=1 "Gray (Haute-Saône) (not yet redacted)"): the suspension bridge (104 m long).
The first chain bridge on the European continent was the Chain Bridge&action=edit&redlink=1 "Chain Bridge (Nuremberg) (not yet drawn up)") in Nuremberg, Germany. The Széchenyi Chain Bridge, which spans the Danube River in Budapest, was also designed by William Clark and is a larger-scale version of the Marlow Bridge.[12].
In 1823 the Saint-Antoine footbridge was built in Geneva")[13] and since 1832, in Freiburg "Fribourg (Switzerland)") the grand pont suspendu")[14] whose 87 kilo drawn wire cables, and used at 27 kilos of breaking tension (parallel strands), allowed a span of 273 m to be reached. Many light bridges were thus built: Bercy and Constantine"), in Paris (101 m), Gray"), Châteaulin"), La Roche-Bernard")... but these bridges moved a lot and therefore the traffic loads had to be limited. They suffered an eclipse in France until the appearance of the rigid beam, which allowed carpentry to carry out works comparable to bridges.[15].
In 1832, Henri Navier established the first rules for the calculation of suspension bridges. Despite the success they assumed, problems began to appear. In 1831, a regiment of soldiers parading over Broughton Bridge in the United Kingdom caused the bridge to vibrate, due to the rhythmic pace of the parade, which caused it to break. Unfortunately, in 1851 a similar disaster was repeated in France, on the Angers bridge, where 200 soldiers died. French engineers did not build a suspension bridge again until 1871, and even today in Europe there is a tendency to avoid building them. In America it was not like that, the suspension bridges were very successful. In 1842 the Fairmount Cable Bridge in Philadelphia was completed with a span of . At the end of the century the United States had perfected the construction of the suspension bridge until it reached its current enormous dimensions. In 1866, the Roebling Bridge over the Ohio River had a span, in 1869 it was surpassed by the Niagara Bridge with , and in 1883 the Brooklyn Bridge was completed with .
Clifton Bridge (1864) was also built in this way. An interesting variation is the Ferry Bridge at Burton-on-Trent, Staffordshire (1889, by Thornewill and Warham), in which the chains were not attached to the buttresses, as was usual, but were attached to the main beams, which were thus compressed. There the chains were made of flat plates of wrought iron, eight inches (203 mm) wide by one and a half inches (38 mm) thick, riveted together.[16]