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Encyclopedia > Girder bridge
Girder Bridge
Two different girder bridges. The top is a plate girder bridge, while the bottom is a concrete girder bridge.
Ancestor Beam bridge
Related Trestle, truss bridge, moon bridge
Descendant Plate girder bridge
Carries Pedestrians, automobiles, trucks, light rail, heavy rail
Span range Short
Material Iron, steel, concrete
Movable No
Design effort low
Falsework required No

A girder bridge, in general, is a bridge built of girders placed on bridge abutments and foundation piers. In turn, a bridge deck is built on top of the girders in order to carry traffic. There are several different subtypes of girder bridges: A plate girder bridge is a bridge often seen supporting railroad roadbeds over short spans. ... A steel pedestrian footbridge over the a busy road in Swansea, typical of many beam bridges A beam bridge is a direct descendant of the log bridge now made from steel I beams, box beams (hollow rectangular tubes), reinforced concrete, or post-tensioned concrete (concrete with tubes for cable tendons). ... Steel trestle with plate girder spans A trestle is a bridge that consists of a large number of short spans, supported by splayed vertical elements and is usually for railroad use. ... A truss bridge is a bridge composed of connected elements (typically straight) which may be stressed from tension, compression, or sometimes both in response to dynamic loads. ... A decorative bridge in San Franciscos Japanese Tea Garden. ... A plate girder bridge is a bridge often seen supporting railroad roadbeds over short spans. ... This article is about the edifice (it is primarily an index to articles concerning specific bridge types). ... This page is a candidate to be copied to Wiktionary. ...

  • A rolled steel girder bridge is made of I beams that are rolled into that shape at a steel mill. These are useful for spans between 10 meters and 30 meters (33 feet to 100 feet). Rolled steel girders are practically available with a web height of up to one meter (3 feet).
  • A plate girder bridge is made out of (mostly) flat steel sections that are later welded or otherwise fabricated into an I beam shape. Plate girders can have a greater height than rolled steel girders. Plate girder spans can be used for spans between 10 meters and more than 100 meters (33 feet to more than 330 feet). The web (vertical section) of a plate girder can be taller than that of a rolled steel girder, providing greater strength than a rolled steel girder. The thickness of the top and bottom flanges of a plate girder does not have to be constant; the thickness can be changed (typically at a field splice) to save on material costs. Stiffeners are occasionally welded between the compression flange and the web to increase the strength of the girder.
  • A concrete girder bridge is made of concrete girders, again in an I beam shape. The concrete girders can be either prestressed cast concrete or post-tensioned girders. Concrete girder bridges are best for spans between 10 meters and 50 meters (33 feet to 164 feet). Prestressed, precast concrete girders are readily available.
  • A box girder bridge is built from girders in a rectangular box shape instead of an I beam shape.

An I beam bridge is simple to design and build, and works well for straight spans. However, if the bridge needs to be curved, the beams are subject to twisting forces (torque). This can be alleviated by building several shorter, straight spans with a curved bridge deck, or by using box girders. Building metal box girders is more difficult, though, because the welding of the inner corners between the flanges and the webs has to be done either by a robot or a human, depending on who can fit inside. I-beams are beams with an I- or H-shaped cross-section. ... A steel mill at the turn of the century in Pittsburgh, Pennsylvania A steel mill (British English and Australian English steelworks) is an industrial plant for the manufacture of steel. ... A plate girder bridge is a bridge often seen supporting railroad roadbeds over short spans. ... A box girder bridge is a bridge commonly used for roadway flyovers and for modern elevated structures of light rail transport. ... In anatomy, the cuboid bone is a bone in the foot. ...


References

  • (2002). Structural Systems and Dimensions. (pdf) pp. 79 Montana Department of Transportation. URL accessed on 2006-05-05.
  • (2002). Structural Steel Superstructures. (pdf) pp. 42 Montana Department of Transportation. URL accessed on 2006-05-08.
  • (1999). Bridge Types - Girder. Matsuo Bridge Co., Ltd.. URL accessed on 2006-05-05.

 
 

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