General Information
Figure 1 shows a suspension bridge that is used by motorcycles, bicycles and pedestrians.
![Suspension bridge over a river](bridges/suspension-bridges/bridge-9/1-suspension-bridge.jpg)
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.
![Wind guy system of a suspension bridge](bridges/suspension-bridges/bridge-9/2-lateral-cables.jpg)
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](bridges/suspension-bridges/bridge-9/3-cross-section.jpg)
Girder
Figure 4 shows a schematic partial three-dimensional view of the steel structure of the main span.
![Three dimensional drawing of the main span steel structure.](bridges/suspension-bridges/bridge-9/4-3d-view.jpg)
The girder layout is longitudinal, and the distance between the hanger cables s ≅ 4.5 m.
Girder-to-Girder Connection
Figure 5 shows a side view of a main span sector.
![Main span sector with longitudinal I-girder.](bridges/suspension-bridges/bridge-9/5-main-span.jpg)
Enlarged view 1 is shown in figure 6.
![Girder-to-girder connection.](bridges/suspension-bridges/bridge-9/6-girder-to-girder.jpg)
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 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.](bridges/suspension-bridges/bridge-9/7-pylon.jpg)
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](bridges/suspension-bridges/bridge-9/8-pylon.jpg)