General Information

Figure 1 shows a pedestrian cable-stayed bridge.

Cable-stayed bridge.
Pedestrian cable-stayed bridge over a creek
Type Single-span cable-stayed bridge
Main span ≅ 12 m
Deck width ≅ 0.8 m
Girder Steel square hollow beam
Pylon Steel (portal shaped)
Stay cable arrangement Radial (two cable planes)

Stay Cable Arrangement and Inclined Members

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

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

There are a total of 10 stay cables: 6 front and 4 back stay cables. The front stay cable arrangement is asymmetric: four are connected to pylon 1, and two are connected to pylon 2. Each pylon connects two back stays inclined in two planes; they converge toward the mid-span axis of the bridge width. Pylon 1 and the main span are also connected by two inclined members with a rectangular hollow cross-section.

  • What are some possible reasons for the asymmetric stay cable arrangement?
    What is the purpose of the inclined members?

    • Stay Cables

    A cable plane is marked in figure 3.

    Cable-stayed bridge.
    Stay cables of a pedestrian cable-stayed bridge

    Each cable plane consists of five stay cables: 1, 3, and 5 are made of a steel wire rope, while 2 and 4 are made of a steel round bar.

  • What are some possible reasons for using steel wire ropes and round bars instead of steel wire ropes or round bars only?

    • Stay Cables Anchorages

    The stay cables are anchored to the girder as shown in figure 4.

    Stay cables anchorages.
    Anchorage at the girder

    Stay cables 2 and 4 (round bars) are anchored to the girder by welding: stay cable 2 has a bent termination, while stay cable 4 has an unbent termination. Stay cable 3 (wire rope) is looped once around the girder; the termination consists of a single U-bolt clamp. Stay cables 3 and 4 are overlapping each other.

  • Does the anchorage of stay cable 2 behave like the anchorage of stay cable 4?
    What is the purpose of overlapping stay cables 3 and 4?

    • Stay Cables Vibrations

    Figure 5 shows the bridge.

    Cable-stayed bridge.
    Pedestrian cable-stayed bridge

    Video 1 shows front stay cables 4 and 4.1 during hand-induced vibration.

    Video 1. Front stay cables 4 and 4.1 during hand-induced vibration.

    The vibration amplitude of stay cable 4 is smaller than the vibration amplitude of stay cable 4.1.

  • Does stay cable 4 carry the same load as stay cable 4.1?

    • Main Span Deflection

    Figure 6 shows a side view of the bridge.

    Cable-stayed bridge.
    Main span deformation of a pedestrian cable-stayed bridge

    The vertical deflection in the mid-span region d ≅ 0.3 m.

  • What are some possible reasons for the above shown deflection?

    • Main Span Cross-Section

    Figure 7 shows a schematic partial cross-section of the main span.

    Cross-section.
    Main span cross-section of a pedestrian cable stayed bridge

    There are one central and two external beams with a rectangular hollow cross-section. The front stays are connected to the external beams. Figure 8 shows the bridge viewed from below.

    Cable-stayed bridge.
    Bottom view of a pedestrian cable-stayed bridge
  • Does the bridge have a structural safety or serviceability problem without the central beam?

    • Construction Phase

    Figure 9 shows a bridge sector.

    Cable-stayed bridge.
    Pedestrian cable-stayed bridge in the shore region

    The pylon is placed over the external girder beams.

  • When were the pylons and stay cables erected?

    • Efficient Span Range

    A steel twin girder bridge as an alternative structural variant and the used cable-stayed bridge are shown in figure 10.

    Schematic three-dimensional views.
    Three dimensional drawings of a cable-stayed bridge and a steel twin girder bridge
  • Which type of bridge would probably have the most efficient span range?
    What are some possible reasons for choosing the applied cable-stayed bridge instead of a steel twin girder bridge?

    • © Copyright 2022 - 2024, all right reserved, used with permission.