General Information

Figure 1 shows a pedestrian suspension bridge.

Pedestrian suspension bridge.
Pedestrian suspension bridge over a river.
Type Three-span suspension bridge
Main span ≅ 60 m
Deck width ≅ 1.5 m
Deck width to main span ratio ≅ 1:40
Pylon Reinforced concrete (H-shaped) with two steel cantilever lateral trusses
Girder Steel half-through truss

Lateral Cables

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

Three-dimensional view.
Three-dimensional drawing of a pedestrian suspension bridge with lateral cables.

The bridge has two lateral cables; they are connected to the anchorages (1), the steel columns—only on shore 1—(A and B), the free ends of the cantilever lateral trusses (2), and the girder in the mid-span region (3). Figure 3 shows a lateral cable between the anchorage (1) and the cantilever lateral truss (2) on shore 1.

Anchorage–cantilever lateral truss sector (shore 1).
Lateral cable between the anchorage and the cantilever lateral truss.

Column A is based on the ground, while column B is based on the top of a reinforced concrete yard wall. Figure 4 shows the above shown lateral cable sector viewed from the bridge.

Anchorage–cantilever lateral truss sector.
Lateral cable layout with horizontal deviation angle.

A horizontal deviation angle α on column B is noticeable. Figure 5 shows a column to lateral cable connection.

Column to lateral cable connection.
Connection between lateral cable and column.
  • What are the main structural problems?

    • Figure 6 shows a lateral cable between the cantilever lateral truss and the main span mid-region viewed from shore 1.

    Cantilever lateral truss–main span mid-region sector.
    Lateral cable in the main span region.

    The lateral cable is sagging.

  • What is the purpose of lateral cables?

    • Main Cable Anchorage

    Figure 7 shows a main cable anchorage on shore 1.

    Main cable anchorage (shore 1, front view).
    Main cable anchorage of a pedestrian suspension bridge.

    The main cable is connected to the anchor block by two embedded anchor rods (joined by a pin) and a U-shaped plate. Figure 8 shows the back connection of the U-shaped plate on shore 1, while figure 9 shows the back connection on shore 2.

    U-shaped plate to anchor block connection (back view, shore 1).
    Anchor block to shaped plate connection.

    The U-shaped plate connects the back-end of the anchor block.

    U-shaped plate to anchor block connection (back view, shore 2).
    Anchor block to shaped plate connection.

    The U-shaped plate does not connect the back-end of the anchor block like on shore 1.

  • What are some possible structural and/or constructive reasons for the U-shaped plate to anchor block connection difference?
    Does the bridge have a structural safety or serviceability problem without the U-shaped plates?

    • Half-Through Truss

    Figure 10 shows a side view of a half-through truss sector.

    Half-through truss.
    Half-through truss girder with gaps.

    The half-through truss consists of separate units. Figure 11 shows two schematic partial lateral views of the half-through truss with and without a gap.

    Half-through truss.
    With gap Without gap
    Schematic drawings of two types of half-through trusses.
  • What are the main structural differences between the two half-through trusses?
    How does the distance between the hanger cables affect the structural behavior of the half-through trusses?

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