General Information

Figure 1 shows a cable-stayed bridge that is used by motorcycles, bicycles and pedestrians.

Cable-stayed bridge.
Cable-stayed bridge over a river
Type Single-span cable-stayed bridge
Main span ≅ 27 m
Deck width ≅ 1.5 m
Girder Steel twin C-girder (cold formed)
Pylon Reinforced concrete and steel (portal shaped)
Stay cable arrangement Radial (two cable planes)

Arrangement of Stay Cables

Figure 2 shows a schematic partial three-dimensional view of the bridge.

Three-dimensional view.
Three-dimensional drawing of a cable-stayed bridge

There are a total of 24 stay cables: 20 front and 4 back stay cables. Stay cables 5 and 6 are anchored to the C-girder at the same position, as shown in figure 3.

Mid-span stay cable arrangement.
Arrangement of stay cables in the mid-span region
  • What are some possible reasons for anchoring stay cables 5 and 6 at the same position?
    What is another possible arrangement?
  • Stay Cables Anchorages

    Figure 4 shows a stay cable to C-girder anchorage.

    Anchorage at the C-girder (side view).
    Anchorage at the girder

    The stay cables are anchored at the C-girder by a turnbuckle and a multi-bent rebar. The C-girder has a hole in the web region through which the multi-bent rebar passes. Figure 5 shows an anchorage viewed from above.

    Anchorage at the C-girder.
    Anchorage at the girder
  • What are the main structural problems?
  • Figure 6 shows a further anchorage viewed from above.

    Anchorage at the girder.
    Anchorage at the girder

    The multi-bent rebar has a different shape than the multi-bent rebar in figure 5.

  • Does the anchorage in figure 6 behave like the anchorage in figure 5?
  • The stay cables are anchored to the pylon as shown in figure 7.

    Anchorage at the pylon.
    Anchorage at the pylon

    The stay cables are anchored at the pylon top by a single embedded U-bar; the front stays are stacked one on top of the other. Figure 8 shows a schematic partial-cross section of the pylon top region.

    Pylon cross-section (top region).
    Pylon top cross section of a cable stayed bridge
  • What is a possible failure mode?
  • Wire Rope Termination

    Figure 9 shows a stay cable end in the main span region.

    Stay cable end (main span region).
    Wire rope termination using cable clips

    Each stay cable is made of a steel wire rope, and the termination consists of U-bolt clamps. The U-parts are on the live end of the wire rope, and there is no wire rope thimble between the turnbuckle and the wire rope. Each front stay cable has three U-bolt clamps: two are used for the girder anchorage, and one is used for the pylon anchorage, as shown in figure 10.

    Stay cable end (pylon region).
    Wire rope termination using cable clips
  • What affects the termination efficiency of a steel wire rope when using U-bolt clamps?
  • Stay Cable Vibration

    Figure 11 shows the bridge viewed from the mid-span region.

    Mid-span region.
    Mid-span region of a cable-stayed bridge

    The stay cables are sagging. Video 1 shows stay cable 5 during hand-induced vibration.

    Video 1. Stay cable 5 during hand-induced vibration.
  • How much load does stay cable 5 carry?
  • Suspended Bridge

    A suspended bridge as an alternative variant and the used cable-stayed bridge are shown in figure 12.

    Schematic three-dimensional views.
    Three-dimensional drawings of a cable-stayed bridge and a suspended bridge
  • What are the main structural and constructive differences between the two bridges?
    What are some possible reasons for choosing the above shown cable-stayed bridge instead of a suspended bridge?