engleski

TWIN BRIDGES ACROSS RJEČINA RIVER CANYON

A new bridge is to be built parallel to and south of the Rječina Bridge of the Rijeka city beltway, built in 1984. This bridge will provide two-lane eastbound traffic, while its existing north twin will maintain the two-lane westbound traffic. Both north and south bridges were designed already in the 1970’ s. The north bridge was opened to traffic in 1988, while the construction of its southern twin was postponed. Recently the growing congestion on the Rijeka beltway called for the construction of the new bridge, parallel to the existing crossing to upgrade the single-carriageway road to motorway standards. The 30-years old original design of the south Rječina Bridge fixed its layout and proportions. However, the bridge design had to be adjusted to currently valid code (Eurocode) provisions and requirements, while preserving the resemblance to the existing neighbouring structure. The new Rječina Bridge is a prestressed concrete rigid strut frame structure with the box type superstructure. The superstructure is continuous over three spans, with the main span of 108.5 m and with two identical side spans of 50 m each. Its new design exemplifies more stringent requirements on bridge structures, incorporated in current structural standards in comparison to standards valid about thirty years ago, which is discussed in this paper. It should be noted that the old bridge is still in a rather good condition with some visible damage confined to bridge equipment only.

Strut frame bridge; twin bridges; bridge design; design standards evolution

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