General Information

Figure 1 shows a suspension bridge that is used by motorcycles, bicycles and pedestrians.

Suspension bridge.
Suspension bridge over a river
Type Single-span suspension bridge
Main span ≅ 130 m
Deck width ≅ 2 m
Deck width to main span ratio ≅ 1:65
Pylon Reinforced concrete (H-shaped)
Girder Steel twin I-girder

Wind Guy System

Figure 2 shows a side view of the main span.

Main span.
Wind guy system of a suspension bridge

The shore anchored wind guy cable is connected to the I-girder by the wind ties. There are a total of two wind guy cables (one per side) and 26 wind ties (13 per side). Figure 3 shows a schematic partial cross-section of the bridge.

Cross section of a suspension bridge with wind guy cables and wind ties
  • Which technical factors affect the decision-making process for using a wind guy system or not?
  • Girder

    Figure 4 shows a schematic partial three-dimensional view of the steel structure of the main span.

    Three-dimensional view.
    Three dimensional drawing of the main span steel structure.

    The girder layout is longitudinal, and the distance between the hanger cables s ≅ 4.5 m.

  • What are some possible reasons for using a longitudinal girder instead of a transverse girder?
  • Girder-to-Girder Connection

    Figure 5 shows a side view of a main span sector.

    Main span.
    Main span sector with longitudinal I-girder.

    Enlarged view 1 is shown in figure 6.

    Enlarged view 1.
    Girder-to-girder connection.

    The girder-to-girder connection consists of two web plates and a single nut-bolt, which is placed at the mid-height of the I-girder. The bottom flanges are at different elevations (h1 ≠ h2), and there is an increasing free space —top to bottom—between the webs.

  • What types of stresses can be transferred from girder-to-girder with the above shown connection?
    What are some possible reasons for the different elevations of the bottom flanges?
  • Back Stay Cables

    Figure 7 shows a pylon viewed from the front.

    Front view of a reinforced concrete H-shaped pylon.

    Besides the main cables, each pylon is connected to four back stay cables (marked by the numbers 1 to 4). Figure 8 shows a side view of the back stays to pylon connection region.

    Back stays to pylon connection region.
    Back stays to pylon connection region
  • What are some possible reasons for using the back stay cables?