It is not a secret that the bridges, tunnels, overpasses are one of the oldest engineering inventions of mankind. In ancient times, a couple of logs across the river or any physical barrier were very birth of engineering idea about the bridge construction technology.
Nowadays it is impossible to provide the existence of mega-cities, cars and railways without the bridges. Modern technology allows the construction of bridges to build complex bridge structures quickly and accurately.
Bridge building can be traced back several thousand years. In primitive times, man used fallen trees, arches made of a rock fall and suspension bridges made of vines and creepers to cross streams and ravines. These are the three natural forms of bridging methods, namely, the beam, the arch and the suspension structure. Despite the technological advances of the recent past, these three forms, either singularly or in combination, remain the basis of all bridge construction.
The vast majority of arch bridges were built with stone masonry. A few were also built of iron. Some examples of these will be presented during the lecture. Modern arch bridges are built with reinforced concrete and therefore only die construction of reinforced concrete arch bridges will be considered in this paper.
Suspension bridges are used to form exceptionally large Spans. They are a highly specialized form of construction and far more expensive than beam bridges. Their use is therefore limited to a small quantity of applications where their ability to span large distances is paramount.
Beam bridges are by far the most widely used form of bridge construction. They are applicable to small span bridges as well as large spans of around 150m in prestressed precast concrete and spans of around 200m in steel box girder form. In certain circumstances larger spans have been achieved with these forms of construction. Traffic requirements in many parts of the world have made grade separation necessary at junctions. Generally, such grade separations require the construction of small to medium span bridges or flyovers for which beam type bridges are the most appropriate. The techniques of construction of this form of bridges will therefore be considered in detail (Barr, 2006).
Since concrete is the most popular material for bridge construction, emphasis will be given to concrete bridges.
– Bridges classified by structural configuration
– Common bridge construction methods