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
Stay cable arrangement Radial (two cable planes)

Arrangement of Stay Cables

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

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

The bridge has 20 front and 4 back stays. Stay cables 5 and 6 are anchored to the girder at the same location, as shown in figure 3.

Mid-span stay cable arrangement.
Arrangement of stay cables in the mid-span region
  • What are some possible reasons to anchor stay cables 5 and 6 at the same location?
  • Girder Anchorages

    Figure 4 shows a girder anchorage.

    Girder anchorage (side view).
    Anchorage to the girder

    The anchorage consists of a turnbuckle (open body) and a multi-bent rebar. The girder has a web hole, through which the multi-bent rebar passes.

  • What are the main structural problems?
  • Figures 5 and 6 show two anchorages viewed from above.

    Girder anchorage (1).
    Anchorage to the girder

    The multi-bent rebar has a closed hook, and the turnbuckle is of closed body type. The wire rope termination consists of U-bolt clamps with the U-parts positioned on the live end of the cable. The stay and the turnbuckle are directly connected (without a cable thimble).

    Girder anchorage (2).
    Anchorage at the girder

    The multi-bent rebar has an open hook, and the turnbuckle is of open body type; the U-parts are alternately positioned.

  • What are some possible reasons for the different anchorages?
    Does anchorage 1 structurally behave like anchorage 2?
  • Pylon Anchorage

    The stay cables are anchored to the pylon as shown in figure 7.

    Pylon anchorage.
    Anchorage at the pylon

    The stays are anchored to the pylon's top end by a U-anchor, and the front stays are stacked one on top of the other. Stays and the U-anchor are directly connected. Figure 8 shows a schematic cross-section of the anchorage region.

    Cross-section (pylon anchorage).
    Pylon top cross section of a cable stayed bridge
  • What are the main problems?
  • Stay Cable Vibration

    Figure 9 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 is transferred from the girder to the pylon by stay cable 5?
  • Suspended Bridge

    A suspended bridge as an alternative variant and the used cable-stayed bridge are shown in figure 10.

    Cable-stayed bridge and suspended bridge.
    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 cable-stayed bridge instead of the suspended bridge?