Bridge:-
Structure that spans horizontally between supports, whose function is to carry vertical loads. The prototypical bridge is quite simple—two supports holding up a beam—yet the engineering problems that must be overcome even in this simple form are inherent in every bridge: the supports must be strong enough to hold the structure up, and the span between supports must be strong enough to carry the loads. Spans are generally made as short as possible; long spans are justified where good foundations are limited—for example, over estuaries with deep water.
All major bridges are built with the public’s money. Therefore, bridge design that best serves the public interest has a threefold goal: to be as efficient, as economical, and as elegant as is safely possible. Efficiency is a scientific principle that puts a value on reducing materials while increasing performance. Economy is a social principle that puts value on reducing the costs of construction and maintenance while retaining efficiency. Finally, elegance is a symbolic or visual principle that puts value on the personal expression of the designer without compromising performance or economy. There is little disagreement over what constitutes efficiency and economy, but the definition of elegance has always been controversial.
Generally speaking, bridges can be divided into two categories: standard overpass bridges or unique-design bridges over rivers, chasms, or estuaries. This article describes features common to both types, but it concentrates on the unique bridges because of their greater technical, economic, and aesthetic interest
The Elements Of Bridge Design
There are six basic bridge forms: the beam, the truss, the arch, the suspension, the cantilever, and the cable-stay.
Beam
The beam bridge is the most common bridge form. A beam carries vertical loads by bending. As the beam bridge bends, it undergoes horizontal compression on the top. At the same time, the bottom of the beam is subjected to horizontal tension. The supports carry the loads from the beam by compression vertically to the foundations.
When a bridge is made up of beams spanning between only two supports, it is called a simply supported beam bridge. If two or more beams are joined rigidly together over supports, the bridge becomes continuous.
Bridge Engineering – Components of Bridge Structures
A bridge is a structure providing passage over an obstacle without closing the way beneath. The required passage may be for a road, a railway, pedestrians, a canal or a pipeline. The obstacle to be crossed may be a river, a road, railway or a valley.
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components of bridge
Classification of Bridges
Classification of Bridges (According to form (or) type of superstructures)
- Slab bridge
- Beam bridge
- Truss bridge
- Arch bridge
- Cable stayed (or )suspended bridge
Classification of bridges (According to material of construction of superstructure)
- Timber bridge
- Concrete bridge
- Stone bridge
- R.C.C bridge
- Steel bridge
- P.C.C bridge
- Composite bridge
- Aluminum bridge
Scherzer Rolling Lift Bridge
Classification of bridges (According to inter-span relationship)
- Simply supported bridge
- Cantilever bridge
- Continuous bridge
Classification of bridges (According to the position of the bridge floor relative to superstructures)
- Deck through bridge
- Half through or suspension bridge
Classification according to method of connection of different part of superstructures
- Pinned connection bridge
- Riveted connection bridge
- Welded connection bridge
New River Gorge Bridge made of weather resistant steel
According to length of bridge
- Culvert bridge(less than 6 m)
- Minor bridge(less than 6 m-60m)
- Major bridge(more than 60 m)
- Long span bridge(more than 120 m)
According to function
- Aqueduct bridge(canal over a river)
- Viaduct(road or railway over a valley or river)
- Pedestrian bridge
- Highway bridge
- Railway bridge
- Road-cum-rail or pipe line bridge
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