Types of Bridges
There are six major types of bridges. Beam, Arch, Suspension, Cable-stayed, Cantilever, and Truss. The beam type of bridge is the simplest type of bridge. It could be simple to a piece of wood supporting it or a more complex structure. It is made of two or more supports which hold up beams. The beams top surface is compressed while the bottom edge is under tension. The arch bridges have weight carried outward along two paths which curve toward the ground. They have been around for thousands of years. Arch bridges have been made out of brick or stones. The suspension bridges have cables hanging from towers. The cables transfer weight from the trafficway road to the cables, and then to the towers. They tend to be the most expensive to build and most are made of iron. Cable-stayed bridges have towers, but cables from the towers go directly to the road deck, instead of being connected tower to tower. There is a harp design, and a fan design. Truss bridges are formed with rigid frame work. The walls are formed into a triangular shape and modern truss' are made of steel.