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Bridge built of girders placed on bridge abutments and foundation piers From Wikipedia, the free encyclopedia
A girder bridge is a bridge that uses girders as the means of supporting its deck.[1] The two most common types of modern steel girder bridges are plate and box.[citation needed]
![]() Two different girder bridges. The top is a plate girder bridge, while the bottom is a concrete girder bridge. | |
Ancestor | Beam bridge |
---|---|
Related | Trestle bridge, truss bridge, moon bridge |
Descendant | Box girder bridge, Plate girder bridge |
Carries | Pedestrians, automobiles, trucks, light rail, heavy rail |
Span range | Short, Medium |
Material | Iron, wood, concrete |
Movable | No |
Design effort | low |
Falsework required | No |
The term "girder" is often used interchangeably with "beam" in reference to bridge design.[2][3][4][5] However, some authors define beam bridges slightly differently from girder bridges.[6]
A girder may be made of concrete or steel. Many shorter bridges, especially in rural areas where they may be exposed to water overtopping and corrosion, utilize concrete box girder. The term "girder" is typically used to refer to a steel beam. In a beam or girder bridge, the beams themselves are the primary support for the deck, and are responsible for transferring the load down to the foundation. Material type, shape, and weight all affect how much weight a beam can hold. Due to the properties of the second moment of area, the height of a girder is the most significant factor to affect its load capacity. Longer spans, more traffic, or wider spacing of the beams will all directly result in a deeper beam. In truss and arch-style bridges, the girders are still the main support for the deck, but the load is transferred through the truss or arch to the foundation. These designs allow bridges to span larger distances without requiring the depth of the beam to increase beyond what is practical. However, with the inclusion of a truss or arch the bridge is no longer a true girder bridge.
Girder bridges have existed for millennia in a variety of forms depending on resources available. The oldest types of bridges are the beam, arch and swing bridges, and they are still built today. These types of bridges have been built by human beings since ancient times, with the initial design being much simpler than what we utilize today. As technology advanced the methods were improved and were based on the utilization and manipulation of rock, stone, mortar and other materials that would serve to be stronger and longer.
In ancient Rome, the techniques for building bridges included the driving of wooden poles to serve as the bridge columns and then filling the column space with various construction materials. The bridges constructed by Romans were at the time basic but very dependable and strong while serving a very important purpose in social life.
As the Industrial Revolution came and went, new materials with improved physical properties were utilized; and wrought iron was replaced with steel due to steel's greater strength and larger application potential.
All bridges consist of two main parts: the substructure, and the superstructure. The superstructure is everything from the bearing pads, up - it is what supports the loads and is the most visible part of the bridge. The substructure is the foundation which transfers loads from the superstructure to the ground. Both must work together to create a strong, long-lasting bridge.
The superstructure consists of several parts:
The substructure is made of multiple parts as well:
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