Szechenyi Chain Bridge
The Széchenyi Chain Bridge (Hungarian: Széchenyi lánchíd) spans the River Danube between Buda and Pest, the western and eastern sides of Budapest. Designed by William Tierney Clark and built by Adam Clark, it was the first permanent bridge across the Danube in Hungary. The bridge bears the name of István Széchenyi, a major supporter of its construction, but is most commonly known as the "Chain Bridge".
Length if centre span: 202 metres (663 ft).
1849 The bridge was completed. William Tierney Clark said of it:
"Thus was finished Pesth Suspension Bridge, a work which, in its construction, encountered probably more difficulties than any structure of a similar kind in existence; the magnitude of the river over which it is thrown, its depth, the nature of its bed, and the velocity of the current, created misgivings, at one time almost universal in Hungary, that no permanent communication could ever be established across the Danube, between Buda and Pesth.
'The moral difficulties to be overcome, no less than the physical obstacles, were very great; pride, prejudice, and jealousy had each to be encountered, so universally against the object at one period, that nothing less than the extraordinary energy and perseverance shown by Count Szhchenyi could have withstood their evil effects, and few would have made the attempt."[1]
The bridge's structure was upgraded and strengthened in 1914. In World War II, the bridge was blown up on 18 January 1945 by the retreating Germans during the Siege of Budapest, with only the towers remaining. It was rebuilt, and reopened in 1949.
A remarkable online archive of documents and drawings reating to the original structure is available here [2]. An interesting example here shows the arrangement of the single-piece iron castings which extended the width of the bridge, connecting the suspenders to support the road and pavement decks. This drawing shows the arrangement of rollers supporting the chains as they pass over the towers. Here the chain links, instead of being straight are curved. The upper chain links are supported by six rollers, and the lower links by seven rollers. The wrought iron rollers are reduced to 10 inches in diameter at the ends and sit in journals in the cast iron base. The base casting is 6 ft 6" wide and about 14 ft long.
Reconstruction
During the renovation between 1913 and 1915, practically the entire superstructure was replaced, i.e. everything except the pillars. The old chain could not support the weight of the new steel deck, so it was replaced by steel links of twice the cross sectional area. The bridge also received lattice steel bracing beams.
The portals of the columns were discretely widened by 1 m. The portals initially had parallel sides, but were tapered to match the outer sloping walls. Three-quarters of the chains are around 100 years old, while the deck structure is only 70 years old.
The new structure could withstand a distributed load of 400 kg/m². During the reconstruction between 1947 and 1949 after World War II, 76% of the chains were reused and the bridge received a completely new deck structure and bracing beams.
The above information is condensed from an excellent blog from 2020 [3]