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The Cable-stayed Bridge
How the Cable-stayed bridge works.
When you look at the Cable-stayed, you may think that it looks like just a variant of the suspension bridge, but don't let the similar towers and hanging roadways fool you!
Cable-stayed bridges differ from suspension bridges because they don't require anchorages, or even two towers. Instead, the cables run from the roadway up to a single tower that alone bears the weight.
The tower or pylon is responsible for absorbing and dealing with compressive forces that are transferred to earth. So the cables are in tension, and the towers are in compression.
The cables attach to the roadway in different ways.
For example the cables may be attached to the roadway in a radial pattern; cables extend from several points on the road to a single point at the tower, like numerous fishing lines attached to a single pole.
Or the cables may be attached to the roadway in a parallel pattern, the cables attach to both the roadway and the tower at several separate points.
Engineers constructed the first cable-stayed bridges in Europe in the 1940s, although, like all bridges today, examples can be seen in very early history.
Cable-stayed bridges are a popular choice for engineers as they offer all the advantages of a suspension bridge but at less cost for spans of 152 to 853 meters. They require less steel cable, are faster to build and incorporate more precast concrete sections.
DRAWING CHALLENGE:- PRODUCE DRAWINGS AND SKETCHES OF CABLE-STAYED BRIDGES.
The cable-stayed bridge does not have to have anchorage points or even two towers, as a result design engineers and architects have produced cable-stayed bridges in a wide range of styles.
Challenge yourself to draw a range of possible designs for a cable-stayed bridge.
This will be the last bridge that you make a model of. Think about all you have learned about making bridge models, and as you sketch, maybe you should be thinking that this will be the best model yet!
PRACTICAL CHALLENGE:- MAKE A MODEL OF A CABLE-STAYED BRIDGE
In this challenge you will be given access to card, wooden blocks, string and dowel.
You will also be given access to glue guns, pillar drill, cordless drill, scissors and modelling tools and equipment.
Make and test a model of a Cable-Stayed bridge that spans a 300mm gap.
You may work individually, with a partner or in a team.
Handy Hints: the roadway must be secured to the Towers with cables either in parallel or radial patterns, and the cables do not need to be anchored. You may even consider the cycle bridge in Newton Abbot, and does the tower have to be vertical?
Research Exercise: Famous Cable-Stayed Bridges around the world
Carry out research into Cable-stayed Bridges around the world.
Find out the location of the bridge.Find out when the bridge was built.What does the bridge carry? Pedestrians, Trains, Cars, waterway?What material is the bridge made from?What other interesting facts can you find out?How will you present your information?
Handy hint : You may want to focus your research on one or two bridges, for example the Viaduc de Millau, which is the tallest bridge in the world, or even the Town Quay Bridge in Newton Abbot.