Bridge Components and Their Function
What is Bridge:
A bridge is a structure for carrying the road traffic or other moving loads over a deep valley or obstruction such as a river, channel, road or railway.
In Prehistoric times the first bridges were made by spanning the small streams with the help of fallen trees or togs of wood. Afterward, suspension Type Bridge was constructed by twisted creepers tied to tree trunks on either side of a gorge.
Beginning with rope and chain footbridges, science has now developed intensively and extensively and it is one of the major achievements of the engineering genius of mankind.
Importance of bridges:
- Road or railway traffic can run uninterrupted in monsoon
- Saving in time and fuel.
- It improves the aesthetic of a road.
- Distance between two places can be reduced.
- Agriculture products, industrial products, and raw materials can reach the industries quickly which helps in the economic development of the area.
- Construction of a bridge on railway alignment at level crossing reduces the number of accidents.
- Bridges are important from a military point of view.
Bridge Components and Their Function:
The main components of a bridge are
- Adjoining structure
The components of the bridge below the level of bearings is known as Substructure. It consists of the following.
The function of the substructure is to support the superstructure components and transmit their loads safely to the subsoil,
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It is a structure mostly used for bridge and dam as substructure at the ends of a bridge span or dam and on that superstructure is rest. Bridge with a single span has two abutments that offer vertical and lateral support. It also plays the role of retaining walls to resist lateral movement of the earthen fill of the bridge approach.
The abutment can also be defined by the structure supporting one side of an arch, or masonry used to resist the lateral forces.
Piers provide intermediate support between two bridge spans. Bridge piers mainly support the bridge superstructure element and transfer the load to the foundation.
Pier must be strong to handle the horizontal as well as lateral. Piers are known as compression members of the bridge.
iv) Wing walls:
It is one of the earth retaining structures in the bridge. They are located adjacent to the abutments and act as retaining walls. Wing wall retains soil for abutment, roadway and approach embankment, which can be at a right angle to the abutment or splayed at different angles.
(2) Superstructure: ( Bridge Components )
The components of the bridge above the bearing are known as superstructure.
It consists of the following.
i) Beams, girders:
Both have a similar function to support the roadway and prevent bending. Girder is also one type of beam support. Where loads are heave girders are used instead of beam support.
Beam has a rectangle cross-section, whereas girders have composed of I-shaped cross-sections with two load-bearing flanges and web for stabilization.
A bearing is provided between bridge girder and pier cap. The main function of bearing to allow free movement or vibration of the top superstructure and reduce effect stress to reach the bridge foundation.
iii) Arch, Cables:
Arched and Cable both have specified used. Arched are used for arch bridge construction and cable are used for suspension, cable-stayed bridge, etc. For different types of bridge construction arches and cable play a vital role.
iv) Parapet wall, handrail:
The parapet is one of safety component of any bridge which prevent the vehicle from falling off where there is a drop. It is also useful for restricting views, to prevent rubbish from passing below, and to act as noise barriers.
Its top surface of bridge roadway on vehicle travel. It is made of concrete or bituminous road.
3) Adjoining structures:
It consists of the followings:
It is a structured constructed at the starting or ending of any bridge. Its main function is to provide smooth and easy entry or exit from bridge.
ii) Guard stones:
They are used to restrict traffic on the particular lane or sometimes as road railing but are generally positioned to protect a specific object, such as a corner of a street or the side of a gate.