Todoric- Period 2
February 12, 2009
Cable Stayed Bridges
Bridges have come a long way in their history. Every single one of them is different in at least one way. However, the most interesting type of bridge is called a cable stayed bridge. This type of bridge consists of one or more columns called towers or pylons, with cables that come down from them to the deck of the bridge. The bridge can be studied by its types, cables, towers, brother bridges, and forces.
There are two different types of bridges: harp and fan. In the harp design, the cables are made nearly parallel by attaching cables to various points on the tower/towers, so that the height of attachment of each cable on the tower is similar to the distance from the tower along the roadway to its lower attachment. A fan design has cables that all connect to or pass over the top of the towers. This type of bridge can be compared to a cantilever or suspension bridge, going by its structure.
When it comes to the cables of the bridge, steel cables are used most of the time. They are extremely strong and flexible, so the bridge can be held tight but be able to move at the same time. Unfortunately, their flexibility makes them weak to one force of nature: wind. One good thing about these kinds of cables is that they are light weight. Other parts of the bridge can be made from tough yet lightweight materials such as steel. The light weight of the bridge, although dangerous to winds, is an advantage when it comes to an earthquake. Complex calculations must be made so the bridge can stand up to the harsh elements of nature.
The next part of the bridge is the tower(s). These can be classified into four categories: single, double, portal, and A-shaped. There are many more variations of the bridge that distinguish it from other ones. One is the cable arrangements. The two main groups, as said before, are harp and fan. These can be broken down into two more categories: star...