Arch bridges - Computational Analysis and Design of Bridge Structures - page 277

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3450

Figure 9.11 Cross section of the main arch of Yajisha Bridge.

half of the main arch is assembled at a lower position vertically. During
the assembling, side-span arch and counterweight are built. A temporary
construction tower is built on top of the abutment, which is connected to
the foundation with a circular track of a 33-m diameter, allowing later
horizontal rotation. Construction cables and temporary bracings are used
to lift the arch. A temporary joint at the springing is designed and built to
allow the vertical rotation of the arch.
Concrete in the top and bottom ribs is not filled at this stage. Total
vertical lift weight is 2058 tons. The vertical rotation angle is 24.7014°.
Figure 9.12b shows the vertical lifting. After the arch is lifted to the design
position, the temporary joints at springing are fixed by reinstalling top and
bottom cutout ribs. Fixing the vertical joints at the end of this stage is
required to ensure stability in the next stage. After the falsework in the side
span is removed, the half structure is ready to rotate horizontally.

9.2.2.3 Horizontal rotation
The horizontal rotation mechanism comprises of a fixed platform in the bot-
tom and a lateral girder connecting two abutments on upstream and down-
stream sides on the top as the moving part. The rotation axis is located at
the center of the lateral girder. The two half arches in upstream and down-
stream sides are connected laterally and rotated horizontally as a whole.