Types+of+Bridges

===A beam bridge (also called the “girder bridge”) is the simplest kind of bridge. A beam bridge could be as simple as a slab of stone, or a plank of wood, laid across a stream or a brook. Bridges designed with modern infrastructure will usually be constructed from steel or reinforced concrete, or a combination of both.===

===A T-Beam Bridge is a reinforced-concrete bridge consisting of a floor slab monolithic with the supporting beams so that the cross section resembles a series of T beams.This T-Beam Bridge is a great load-bearing bridge. It can also be made from almost any material: from simple wood to modern day metal. No matter which material is used, the bridge is sturdy and very durable. Though this bridge is very durable, it has a big disadvantage compared to an I-beam because it has no bottom flange with which to deal with tensile forces.===

===A plate girder bridge is a bridge supported by two or more plate girders. The plate girders are typically I-beams made up from separate structural steel plates (rather than rolled as a single cross-section), which are welded or, in older bridges, bolted or riveted together to form the vertical web and horizontal flanges of the beam. In some cases, the plate girders may be formed in a Z-shape rather than I-shape. The first tubular wrought iron plate girder bridge was built in 1846-47 by James Millholland for the Baltimore and Ohio Railroad. Plate girder bridges are suitable for short to medium spans and may support railroads, highways or other traffic.===

===Composite Beam Bridges are energy efficient bridges made from lightweight glass-fiber-reinforced composite resin instead of concrete or steel and are roughly 12 meters long. It is said that an estimated 7% of global CO2 emissions come from the making and use of concrete, so if 2’000 bridges were replaced with composite bridges the energy savings would be equivalent to the total annual energy bill of 310,000 households.===

Arch Bridges
=== An arch bridge is a bridge with a deck that carries the load and abutments at each end. They are one of the oldest bridges, around thousands of years old, and they have great natural strength. Before, arch bridges were built from stone or brick, but now they are built from reinforced concrete or steel and the new the material it can make longer bridges with lower spans. ===

**The Natchez Trace Parkway Bridge, Franklin, Tennessee.** ** This bridge, in 1994, is the fist American bridge to be constructed with segments of precast concrete, a highly economical material. ** ** Another thing is that it is designed without spandrels (roughly triangular spaces between the left or right exterior curve of an arch and the rectangular framework surrounding it) ** ** to create a more open and aesthetically pleasing appearance and influence bridge design for years to come. **  ** Bixby Creek Bridge, Monterey, CA. This ** **bridge is the favorite coastal bridge in California. Bixby has been technically sound. It's purposeful and symbolically important to its travelers and public works project. The** **project's environmental concerns** **and aesthetics are important to avoid destraction from the natural beauty of the region.**

 ** The Pont du Gard aqueduct, Nîmes, France ** **This Roman stone is one of the most famous examples of their handiwork.** **It has been said that it was built before the birth of Christ. The bridge is held together by mortar only in its top tier.** **Stones in the rest of the structure stay together by the sheer force of their own weight.**

**The New River Gorge Brid****ge, West Virginia**. **The bridge was finished on October 22, 1977 and the going down on the bridge its 40 mm.****This transformed into a work of structural and the longest steel span in the western hemisphere: the second highest in the U.S.A.**
 * In an arch bridge there is an important piece that is known as the KEYSTONE. **
 * (It is the middle stone in an arch that holds the two sides together.) **

= Suspension Bridges = ===Suspension bridges are the longest bridges in the world. In other words, they span the largest distances. Suspension bridges are constructed with cables riding over one or more towers and a deck hanging from the cables. these cables can be made of steel (the most commonly used), parallel wire, wire rope, or eyebar (chain). Parallel wire works best with very long distances. The reason why these bridges can go so far without collapsing is because they are very high in tension. Unlike most bridges, suspension bridges support themselves by tension instead of compression. This tension is created when the load and the weight of the bridge itself act on the bridge by pulling apart or stretching the cables. ===

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= One of the most well-known suspension bridges is the Golden Gate Bridge in San Francisco, California, which spans 8,981 feet total. =

==== A **simple suspension bridge** (also called the **footbridge**) is the earliest type of suspension bridge. The cables of this bridge are anchored to the ground and the deck of the bridge is flexible. ====



==== A **suspension bridge** (full name, **suspended-deck suspension bridge**) is a bridge in which the deck hangs by the cables, or suspenders. In this type of construction, the cables are attached to the earth at the end. These bridges are not usually flexible which allows them to span very long distances. ====

==== **Self-anchored suspension bridges** are very similar to suspended-deck suspension bridges. The only difference between the two bridges is that the cables are attached to the deck at the end, rather than the earth around it in a sef-anchored suspension bridge. ====