Many different types of engineers work in designing bridges to suit all of our different needs. From mechanical to civil and even materials engineers, many professionals work in creating better and safer bridges. Read the following articles to learn more about bridges and engineering.
- Forces in Bridges
- Types of Bridges
- Famous Bridges of the World
- Bridge Disasters
- Types of Engineering
Types of Bridges
First, let's look at the forces affecting bridges so we can understand how each type of bridge works. You have two major forces acting on a bridge -- tension and compression. Tension is a force that acts to expand or lengthen the thing it is acting on. On the other hand, compression is a force that acts to compress or shorten the thing it is acting on.1
There are three major types of bridges:
- Beam Bridge
- Arch Bridge
- Suspension Bridge
A beam bridge is the simplest of all types of bridges and consists of a horizontal structure with vertical supports at each end. When a load is applied to the structure, the lower part of the bridge is lengthened, or undergoes tension, while the upper part is squeezed, or undergoes compression. In the picture below you see the tension forces marked with red lines while the green lines represent compression forces.2
One major problem with beam bridges is that they have a tendency to bend in the middle when too much weight is applied. Also, beam bridges are no larger than 250 feet since the longer the length of the bridge, the weaker the vertical supports become which can lead to the collapse of the bridge.3
A variation of the beam bridge is the truss bridge, which uses rigid triangles to spread out the compression and tension forces. Truss bridges are longer than simple beam bridges; however, they are still restricted in how long they can be since the longer the bridge the bigger and heavier the trusses are too.4
An arch bridge has a semicircular structure with supports at both ends. Because the only forcing acting on the bridge is compression, arch bridges can support heavy loads easily and are longer than beam bridges.5
Finally, a suspension bridge uses a series of cables that are hung from two towers. The cables in turn support the deck of the bridge. In suspension bridges, you have tension forces acting on the cables, and compression on the towers.6 Due to their unique design, suspension bridges can be up to 7000 feet in length, longer than any other type of bridge.7
To learn more about each type of bridge, visit How Stuff Works: http://science.howstuffworks.com/bridge.htm