Bridge Basics - A Spotter's Guide to Bridge Design. Bridge Basics Because of the wide range of structural possibilities, this Spotter's Guide shows only the most common fixed (non-movable) bridge types. Other types are listed in the Bridge Terminology page. The drawings are not to scale. Additional related info is found on the other Terminology pages which are linked to the left. The four main factors are used in describing a bridge. By combining these terms one may give a general description of most bridge types. span (simple, continuous, cantilever), material (stone, concrete, metal, etc.), placement of the travel surface in relation to the structure (deck, pony, through), form (beam, arch, truss, etc.).
The three basic types of spans are shown below. Examples of the three common travel surface configurations are shown in the Truss type drawings below. Beam and Girder types Simple deck beam bridges are usually metal or reinforced concrete. Many modern bridges use new designs developed using computer stress analysis. Arch types Stephen H. Main Types of Bridges. BUILDING BIG: All About Bridges. Forces Lab Check out how forces affect structures like bridges. Who Builds Big? Meet Miguel Rosales, an architect who designs beautiful bridges, and David Nyarko, an engineer who makes bridges move! Bridge Webography Check out these links to a bevy of bridge resources on the Web. BUILDING BIG: Bridges Learn more about the PBS broadcast program. Buy the DVD. Bridge.
Etymology The Oxford English Dictionary traces the origin of the word bridge to an Old English word brycg, of the same meaning, derived from the hypothetical Proto-Germanic root brugjō. There are cognates in other Germanic languages. History The first bridges were made by nature itself — as simple as a log fallen across a stream or stones in the river. The first bridges made by humans were probably spans of cut wooden logs or planks and eventually stones, using a simple support and crossbeam arrangement. Some early Americans used trees or bamboo poles to cross small caverns or wells to get from one place to another.
A common form of lashing sticks, logs, and deciduous branches together involved the use of long reeds or other harvested fibers woven together to form a connective rope capable of binding and holding together the materials used in early bridges. During the 18th century there were many innovations in the design of timber bridges by Hans Ulrich, Johannes Grubenmann, and others.