Grace's Guide To British Industrial History

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Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 163,469 pages of information and 245,911 images on early companies, their products and the people who designed and built them.

Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 147,919 pages of information and 233,587 images on early companies, their products and the people who designed and built them.

Franz Josef Bridge, Prague

From Graces Guide
This painting, on display in the Old Town Hall in Prague, shows the Franz Josef Bridge in the distance, Charles Bridge in the foreground, and the Ordish-designed footbridge in between
Photo on display in Prague city centre
Photo of a Shand, Mason fire engine on display in Prague National Technical Museum, with bridge in background
Franz Josef Bridge. Date unknown, photo published in 1946. Note that wire cables have replaced the chains

also known as Franz Joseph Bridge and Most Františka Josefa.

Much scope for confusion here, as the bridge, completed as a chain cable suspension and cable-stayed bridge in 1868, was modified as a wire cable suspension and cable-stayed bridge in the 1890s. It crossed the River Moldau, which has been renamed the River Vltava. The bridge was demolished and replaced in 1949-51 by the current concrete arch Stefanik or Stefanik's Bridge (Štefánikův most).

The original bridge was designed by Rowland Mason Ordish, using the Ordish–Lefeuvre system originally intended for the Albert Bridge over the River Thames in London. Engineer František Schön supervised the construction work. Emperor Franz Joseph attended the ceremonies for its opening on 13 May 1868.

The main span was 100 metres (330 feet) long and 9.76 metres (32.0 feet) wide, while the entire structure was over 240 metres (790 feet) long.

The steel chain links were provided by Cammell and Co of Cyclops Works, Sheffield and by A. Howell and Co of Sheffield. C. Wessely (Wesseley?) was the Resident Engineer. [1]

From The Engineer 1868/11/06:-

'The difference between Mr. Ordish's principle and the ordinary system is, that there is no curve in the main chains or bars of the former, as in those of the latter. Hence there is no motion or vertical wave in the roadway from any passing load, except that due to direct tension, and consequent extensibility of the iron by the strain induced by that load. The platform of a bridge constructed on the ordinary principle will deflect or become depressed under the load, from the disturbance of the equilibrium in the curved chains, as the load passes along the bridge. In the Prague bridge this cannot occur, inasmuch as the principle gives rigidity similar to that present in a trussed bridge, where the bottom flanges of the main girders are nearly as long as the tension chains for carrying the platform and moving loads. The main chains being of considerable length are not of themselves able to keep a straight line. They are, therefore, carried by an upper curved chain, from which they are suspended at intervals of about 14ft., this chain having no work whatever to do in carrying the platform. The curved chain was preferred by Mr. Ordish to the use of struts, as being lighter and cheaper, besides which it unquestionably adds to the graceful appearance of the structure. The adoption of this alternative was also judicious, inasmuch as a curved chain never alters its form after it is permanently loaded, that is, it can have no wave nor motion unless a moving load is carried directly along it. In the Prague bridge the straight chains are a permanent and unchangable load, and, therefore, cannot change the form of the curved chain after they have been suspended in their proper position.

'.... On the piers are erected cast iron towers of exceedingly chaste design, and which are not simply ornamental, but useful, inasmuch as by their mere skin alone, and independently of any internal ties or bracing, they carry the chains of the bridge. The two towers on each pier are braced together near the top, so as to form an arch of light and elegant proportions. Each tower carries two independent saddles, which are placed one above the other, the upper one carrying the suspension chains, and the lower the main chains of the bridge. The saddles are carried on rollers, supported on cast iron bedplates of octagonal form, stiffened by ribs, and so constructed that the metal is wholly in compression. ....

'... Wrought iron boxes are rivetted at distances of 82ft. apart along the main girders. These contain steel bosses carrying the 5-in. steel pins, by which the chains are attached to the roadway. The suspension links are placed one on the inside and one on the outside of the main girder, which forms a continuous girder, supported at intervals of 82ft. The main chains consist of flat links, averaging 14ft. in length , each 4in. X 1in. sectional area in the centre. The material used for these links is Howell's homogeneous steel. ....

'It will be seen from the elevation that chains are so arranged as to support the central girder at five intermediate points, and the end girders at one point. At the central point, and those immediately on either side of it, the platform is suspended from the chains by vertical links. At the four points on each side of each tower the chains are directly attached to the girder, thus putting a horizontal strain upon the girders. .... A chain is attached to the web of the main girder, midway between the two flanges, which receives the horizontal strain induced by one of the suspension chains, attached to the web of the girder near the tower, as explained by Fig. 1. The several chains at this point on entering the abutment, are concealed by cast iron toll houses.'

From a 1900 German source [2]: 'On the Ordish-Lefeuvre system .... the Francis-Joseph Bridge over the Moldau at Prague and the Albert Bridge over the Thames at Chelsea, London, were built in 1868 and 1873 respectively. The former, however, with a centre span of about 147 metres (482 feet), has in the meantime become so ricketty that in 1898 it was considered necessary to replace its unsuitably long and straight flat bars by wire ropes, as well as to strengthen it in other ways.' A footnote states that the work was carried out by Felten and Guilleaume of Mulheim. In 1919, following the fall of the Austro-Hungarian Empire and its monarchy, the bridge was renamed in honour of Milan Rastislav Štefánik. It was further renamed after the Czech composer Leoš Janáček for a short period in the 1940s. The bridge was demolished in 1941 and replaced with a modern one named after Jan Šverma in 1951. The current bridge is again named Stefanik Bridge.

Note: Ordish also designed a pedestrian suspension bridge to cross the River Moldau (Vltava) in Prague between the historic Charles Bridge and the new Franz Josef Bridge. Charles von Wesseley was the Resident Engineer. The bridge had a central tower and a span between abutment faces of 629 ft. The width of the deck was only 11 ft, while the chains were further apart to give improved resistance to wind forces. The main chains were of steel, 1" thick, 4.5" deep, and 21 ft long, made by Cammell of Cyclops Works, Sheffield. The pins were 3.5" diameter. The ironwork was made in Prague.[3]

See Also

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Sources of Information

  1. The Engineer 1868/11/20
  2. [1] A Hundred Years of German Bridge Building by Georg C. Mehrtens, Berlin, 1900, p.35
  3. [2] 'Modern Examples of Road and Railway Bridges : Illustrating the most recent practice of leading engineers in Europe and America' by William H. Maw and James Dredge, partially reprinted from 'Engineering', 1872
  • [3] Wikipedia - Franz Joseph Bridge