Arch Bridge: The Pirna Bridge over the Elbe River
The town of Pirna is situated in the upper Elbe river delta in Saxony. To relieve from non-regional traffic as well as to connect to the planned interstate A17 between Dresden and Prague an outer west drive which includes the new Elbe Bridge Pirna is under construction.
The bridge with a total length of 1,072m consists of two separate superstructures subdivided into three construction segments, each utilizing different technologies.
The left bank approach bridge will be constructed using incremental launching and has a total length of 480m
The 416m river bridge is supported by a reinforced concrete arch connecting to the deck using shear connectors
The 176m long right bank approach bridge will be constructed on falsework
The cross section of all construction segments is a single cell box girder. The approach bridges are post-tensioned in both the longitudinal and transverse directions while the river bridge utilizes a partial stressing of the deck only.
Temporary construction phases required the use of DYWIDAG stressing tendons and tension elements. The reinforced concrete arches of the river bridge were constructed using the free-cantilever method. The cantilevering arch segments were held in place with galvanized DYWIDAG auxiliary strand tendons, tensioned from the pier head in both sides until the load could be transferred to the drive deck. The temporary stays were coupled to DYWIDAG bond head anchorages cast in the arch. The hanging form traveller for the segmental construction of the arch is partially supported by DYWIDAG Threadbars® 36 mm dia. St 835/1035. The elevation of the traveller could be easily adjusted with centre hole jacks for the different construction phases.
The box girder section of the river bridge is composed of a steel web and lower deck with transverse post-tensioned drive deck. The mid span is divided into 5 steel segments, each 22 m to 30 m long. The erection proceeded with a crane on a floating barge: 4 steel segments required auxiliary DYWIDAG strand tendons. The following structural elements were utilized:
steel pylons on the bridge piers with each two concrete pier heads
auxiliary DYWIDAG strand tendons 11 to 15-0.6" (approx. 36 tons total)
galvanized strand tendons 0.6" grade 270 (St 1570/1770), repeated use for both decks tightening strand with DYWIDAG monostrand jacks
final tensioning and elevation fine tuning of individual segments per construction phase with 4 DYWIDAG multistrand jacks type HoZ 3000