Bridges

A bridge is a structure built to span physical obstacles for the purpose of providing passage over the obstacle. Bridges may be classified by how the forces of tension, compression, bending, torsion and shear are distributed through their structure. Here are a few of the many structure types.


Beam Bridge: Beam bridges are the most basic of bridge structures. They are made up of horizontal beams that are supported at each end. The earliest of beam bridges were most likely logs laid out across rivers or other gaps.

Arch Bridge: An arch bridge is a bridge with abutments, or structures built to support lateral pressure on each end shaped as arches. Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. The earliest known arch bridges were built by the Ancient Greeks.

Truss Bridge: A truss bridge is a bridge that utilizes a truss in its a structure. This truss is a structure of connected elements forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads. The truss bridge is one of the oldest structure types that are still commonly used today.

Suspension Bridge: Suspension bridges are suspended from cables. These cables are hung from towers that go very deep down into the ground. The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo.