The new Rappenloch bridge is a single-track prestressed concrete bridge. The total length of the superstructure is about 66m. The cross-section of the box girder bridge is designed as a triangular cross-section in the abutment area and warps towards the middle to a trapezoidal box girder cross-section.
The cross-section height changes from 5.7m to 3.3m. The structure has a longitudinal inclination of 10.5%. The lower edge of the bridge shows a slight arch with a rise of 2.4m.
Due to the Dornbirner Ach running below, a free-span shoring had to be used to build the bridge. Appropriate bearing surfaces were provided below the abutments for this purpose. Due to the limited accessibility caused by the very narrow access road, a shoring system that was as light as possible had to be developed.
The maximum weight of the individual parts in the crown area is limited to approx. four tons, and the full length of the components that can be delivered via the existing road is 12 m.
Due to these boundary conditions, a technically complex shoring had to be developed. We then developed a gently sloping arch support structure consisting of 3 truss tubes. The lattice trusses are restrained to the transoms for assembly and to increase the load-bearing capacity. To ensure the static load-bearing capacity in the concreting state, the shoring had to be braced with tie rods.
Assembly of the falsework
Due to the limited accessibility, the trusses are assembled in small units. We, therefore, decided to mount the lattice trusses so that they cantilevered from both sides. On the Dornbirn abutment side, the inner truss is hung back to an assembly yoke using anchor rods.
Concreting state
The superstructure is made in several concreting steps. We included these construction phases in the static calculation accordingly.
Disassembly
For dismantling, the trusses are hung on the completed superstructure and moved laterally. The components are then dismantled piece by piece.
Conclusion
All planning processes were done in Tekla Structures, including all intermediate states during assembly and disassembly.
