General Information

Figure 1 shows a pedestrian suspended bridge.

Suspended bridge.
Suspended bridge over a creek
Tower-to-tower distance ≅ 15 m
Width ≅ 1 m
Towers Steel and RC (shore 1); wood log, timber, and a tree (shore 2)
Girder Steel transverse beam
Number of walkway cables 2

Structural Concept

Figure 2 shows the bridge.

Suspended bridge.
Suspended bridge over a creek

The girders (A, B, and C) have a length of about 2.5 m, and their bottom sides are directly connected to the walkway cables, which are made of steel wire ropes. Figure 3 shows a bottom view of the bridge.

Bottom view.
 Suspended bridge structure viewed from below

Over the girders are stacked a longitudinal beam (at mid-width), transverse beams, four stringers (1 to 4), and the deck. The side stringers (1 and 4) are connected to the girders by vertical members. The longitudinal beam is made of a rusted H-section, while the remaining parts are made of square hollow sections; they are connected by welding. Figure 4 shows the bridge entrance on shore 1.

Bridge entrance (shore 1).
Tower of a suspended bridge made of H-sections

The tower's columns (A1 and B1) are made of H-sections of different heights (A1 is shorter than B1), and their bases are embedded in RC. The walkway cables pass over the top end of column A and through two web holes on column B; they are anchored (on both shores) to ground-embedded anchor blocks. Figure 5 shows the opposite bridge entrance.

Bridge entrance (shore 2) viewed from the bridge.
Tower of a suspended bridge made of a wood log and a living tree

Column A2 is made of a wood log (ground-embedded base), and the walkway cable passes over its top end; column B2 is made of a living tree, and the walkway cable is connected to it by a vertical cable (steel wire rope). Figure 6 shows the connection between the walkway cable and the living tree.

Walkway cable to tree connection.
Walkway cable to vertical cable Vertical cable to tree
Connections between walkway cable and tree

The walkway cable is directly connected to the vertical cable, which is looped around the trunk over a branch bark ridge and terminated with U-bolt clamps. Figure 7 shows a schematic three-dimensional view of the bridge.

Suspended bridge.
Three-dimensional drawing of a suspended bridge
  • How efficient is the structural concept?
  • Alternative Variant

    Figure 8 shows a schematic three-dimensional view of the bridge and a pony truss bridge variant made of steel.

    Suspended bridge and pony truss bridge.
    Three-dimensional drawings of a suspended bridge and a pony truss bridge

  • What are some possible reasons to choose the suspended bridge?
    Which bridge structural behavior can probably be predicted more precisely and simply?