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 Three-span cable-stayed bridge
Main span ≅ 50 m
Deck width ≅ 2 m
Girder Steel truss
Pylon Reinforced concrete
Stay cable arrangement Fan (two cable planes)

Truss Girder

Figure 2 shows the bridge.

Cable-stayed bridge.
Curved truss of a cable-stayed bridge

The truss girder girder has a slightly curvature and an isosceles trapezoidal cross-section, as shown in figure 3.

Truss girder (shematic three-dimensional view).
Three-dimensional drawing of a truss girder

The truss in made of circular hollow sections and consists of three upper chords, three bottom chords, diagonals, verticals, cross members, and cross braces. The upper base B ≅ 2 m, the bottom base b ≅ 1.4 m, and the height h ≅ 0.8 m. The truss consists of several units that are connected by bolted circular end-plates, as shown in figure 4.

Truss units connection (side view).
Connection between two truss units

The truss does not have diagonals, cross members, and cross braces in the connection region; the verticals' spacing (l) is shorter. Figure 5 shows the used truss girder and a braced twin I-girder as an alternative variant.

Truss girder and braced twin I-girder.
Three-dimensional drawing of a truss girder and a braced twin I-girder
  • What are some possible reasons to choose the truss girder for a 50-meter main span and 2-meter-wide cable-stayed bridge that is used by motorcycles, bicycles, and pedestrians?
  • Stay Cable Bending

    Figure 6 shows a side span.

    Side span.
    Side span of a cable stayed bridge

    The girder anchorage of stay cable 1 viewed from above is shown in figure 7.

    Girder anchorage (stay cable 1).
    Anchorage at the girder

    The girder anchorage is fixed, and stay cable bending is noticeable.

  • What are some possible reasons for the above shown stay cable bending?
    What are the main consequences?