Bridge Wallpapers

Bridge (wallpapers: A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs may be built higher than otherwise needed in order to allow other traffic (particularly ship traffic) beneath. The purpose of a bridge is to allow passage of people, vehicles, trains or ships over an obstacle. The first bridges were spans made of wooden logs or planks and eventually stones, using a simple support and crossbeam arrangement. The arch was first used by the Roman Empire for bridges and aqueducts, some of which still stand today. The Romans also had cement, which reduced the variation of strength found in natural stone. Brick and mortar bridges were built after the Roman era, as the technology for cement was lost but it was refound. During the 18th century, many innovations in the design of timber bridges by Hans Ulrich and Johannes Grubenmann and others. [br]With the rise of the Industrial Revolution in the 19th century, truss systems of wrought iron were developed for larger bridges, but iron did not have the tensile strength to support large loads. With the advent of steel, which has a high tensile strength, much larger bridges were built, many using the ideas of Gustave Eiffel. [br] [br]

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Bridge Wallpapers @ Mega Wallpapers (08 Edition)
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