![What is a Truss?](images/dwarren.png")
A truss is an arrangement of structural that are connected together to form a rigid framework. In most trusses, members are arranged in interconnected triangles, as shown in the example below:
As a result of this configuration, truss members carry load primarily in axial and . Because they are very rigid and they carry load efficiently, trusses are able to large distances with a minimum of material.
Trusses have been used extensively in bridges since the early 19th Century. Early truss bridges were made of wood. The classic American covered bridges are all trusses, though the wooden truss members are covered by walls and a roof, for protection from the elements. Later truss bridges were made of cast iron and wrought iron. Most modern trusses are made of structural steel. Truss bridges can be found in many different configurations, but virtually all have the same basic component parts.
There are many other types of bridges. These include beam bridges, arches, suspension bridges, and cable-stayed bridges.