Bridges

There are four key structural components that a bridge must have: beams, arches, trusses, and suspensions.

1. The beam is the base of the bridge where the cars would drive over. A beam bridge would look like this:

2. The arch distributes compression and diverts weight onto the two column making the arch. An arch bridge looks like this:

3. Trusses provides a more rigid structure and it also helps distribute the weight load more evenly.  Truss bridge look like this:

4. Suspensions are ropes or cables that hold up the roadway. A suspension bridge would look like this:

Bridges all have to deal with two problem: tension and compression. When cars or other weights are placed on a bridge, they compress the bridge downward due to gravity. Therefore, as the bridge is compressed down, it is pulled both ways by the structures at the end and the bridge's tension increases. The tension increasing could be related to tug-of-war game where both sides are pulling at the rope.