A bridge is a structure that is used for the transportation of people or vehicles over a large body of water or physical obstruction. There are different types of bridges according to size and structure.
The transportation route may be roadways, railways, cycle tracks, sidewalks, or a combination of both and the obstruction may be river, stream, valley, channel, etc.
Different types of bridges on the basis of Size
- Minor bridge: minor bridges are the bridge in which the total length of the span is greater than 6 m and less than 60 m.
- Major bridge: Major bridges are the bridge in which the total length of the span is greater than 60 m and less than 120 m.
- Long span bridge: Long span bridges are the bridge in which the length of the span is greater than 120 m.
Types of bridges on the basis of Structural System
The arch bridge is one of the most popular types of bridge, it came into use nearly 3000 years ago.
The arch bridge is located at the bottom of the bridge. This types of bridges is supported by forces of compression, carrying some tension under the arch. It is usually made up of stone, concrete, or steel.
The shape of the arch bridge is curved, the load on the curve is not directly applied straight down, but instead, loads are carried along the curve of the arch to the end of supports.
The part of the bridge does not take a high amount of pressure. These supports are called abutments. The abutment can carry entire loads of the bridge and is responsible for holding the arch in a precise position.
Truss bridge is a very popular bridge design. It uses a diagonal connection or loop of most often triangle-shaped posts above the bridge to distribute the forces across the entire bridge structure.
The length of this bridge is between 50m-110m. Trusses are transferring the load from a single point to the wider area.
Usually straight beams can ensure dynamic forces of tension and compression, but by distributing these loads across the entire structure, entire bridges can handle much stronger forces and heavier loads than other types of bridges.
When the loads applied to the truss, the top edge of the bridge posses compression force, and loads are shared among the angled member to supports and then top the soil.
Beam bridges are simply supported bridges consisting of horizontal beams and vertical piers. It is also named a girder bridge.
This bridge is supported by abutment or piers at each end. Beam bridges are constructed using RCC, wood, steel, etc.
The span of this bridge is less than 80 m. This type of bridge is strong enough to bear the load on it.
When the load applied to it, the top edge of the bridge posses compression whereas the lower part of the bridge is stretched and under tension.
Suspension bridges are known for suspension cables that connect between towers. These cable bridges can be made with a long span.
The roadway is hanged using steel cables. The cables are connected to towers and are secured by anchors on both ends of the bridge.
When the load applied to it, the deck slab posses compression force and then travels the rope, cable to transfer the compression to the towers. The towers then transfer the compression directly to the soil by anchors. The span of the suspension bridge is between 150m to 2000m.
The word cantilever refers that the word which is supported only one side and the other end is free. Cantilever bridges are the same as that but one is not free.
Cantilever bridges are constructed in two parts and the two free ends connected to the suspended deck. The span of the cantilever bridge is between 150m – 500m.
When the load is applied on this bridge, the top supports are subjected to a tensional force and bottom supports are subjected to the compression force which makes the bridge to be balanced.
This type of bridge is adopted when the supports cannot be provided at specific positions.
Cable-stayed bridges are modern bridges and it is similar to the suspension bridge. In this type, cables are directly connected to the tower instead of suspended cables. Tension is uniformly acting on the cables.
In this bridge, there are no anchorages to bear the compression and have only one tower to carry the compression. The length of the span of this bridge is between 500m – 1000m.
In this bridge, the cable is directly connected to the roadway at different points. The cable-stayed bridge is more economical as compared to the suspension bridge.
So, these are different types of bridges found according to size and structure.