Jacks Facilitate the Transverse Shifting of a Steel Arch Bridge
Near Kramsach, 45km north-east of Innsbruck, Austria, an existing railway bridge was replaced by a new steel arch bridge. The new arch bridge was erected parallel to the old railway bridge. The transverse shifting of the 3,500t railway bridge into its final position was an unusual challenge.
In contrast to the old structure, the new bridge leads over the A 12 Inntal Motorway with a single, 100m long cantilever span.
The arch and the beams of the new structure consist of steel. The 19m wide deck slab consists of slightly laterally post-tensioned reinforced concrete. The bridge contains 24 elements that were assembled on site. During construction, traffic on the motorway below was protected by a 1,900m² large safety scaffold.
To temporarily support the steel arches, DYWIDAG supplied 63.5mm Ø Gewi Plus Bars that were temporarily installed between the arches and the deck slab as auxiliary bars or hangers. The use of the threadbars was a decisive advantage because it ensured an exact adjustment and correction of the bridge deck’s superelevation. Once construction was completed, the temporary hangers were replaced by forged hangers.
The deck slab consists of 950m³ of concrete. It was poured in one piece from the middle of the roadway in both directions without any joints. For the longitudinal post-tensioning of the roadway slab, DYWIDAG supplied a total of 60 Type MER/MEF 6-4, 101m long Monostrand Tendons with a total weight of 28.6t that were placed in the longitudinal direction before concreting.
DYWIDAG was asked to carry out the shifting of the bridge structure. For this purpose, 4 temporary Type 22-0,62" and 27-0,62" DYWIDAG Strand Tendons were installed between the new bridge structure and a temporary abutment. Afterwards, 4 large DYWIDAG Tensioning Jacks with hydraulic pumps were supplied and put in place.
Thanks to the excellent cooperation of all of the partners involved in the construction of the bridge, the structure was successfully shifted into its final position.