Types of bridges

TYPES OF BRIDGES

 

1. ACCORDING TO THE CONSTRUCTION MATERIALS

1. Masonry Bridges

Masonry Arch Bridges are commonly used for road bridges of moderate spans. There are two classes of masonry arches, viz., (i) Stone Masonry Arch and (ii) Brick Masonry Arch

2. R.C.C. Bridges

Concrete is very suitable for withstanding compressive loads. Steel is very suitable for tensile loads. The combination of these two is an ideal material for civil structures. Examples: Slab Bridges, T-beam and Slab Bridge, Continuous R.C.C. Bridge, Balanced Cantilever R.C.C. Bridge, R.C.C. Arch Bridge, Rigid Frame R.C.C. Bridge, etc.

3. Pre-stressed Concrete Bridges

The advantages of pre-stressed concrete bridges are: Higher load carrying capacity and Fewer expansion joints. The pre-stressed members are light. Pre-stressing technique increases the shear capacity of concrete. This enables the use of thinner webs, thereby resulting in saving in dead weight. Dead weight is particularly significant in long span bridges. Pre-stressing technique eliminates the cracking of concrete.

4. Steel Bridges

Steel Bridges are built for carrying a highway, a railway track, for support of water pipes, gas or oil pipes, etc. For railway bridges, steel is used from very small spans to very large spans.

5. Timber Bridges

Timber Bridges are Temporary Bridges, which are explained later.

6. Composite Bridges

Composite construction is made of structural elements which are made of two dissimilar elements, e.g., rolled steel joints toped by a cast-in-situ R.C.C. slab, pre-cast R.C.C. or prestressed concrete girder with cast-in-situ R.C.C. slab, etc. Rolled steel joints toped by a cast-in-situ R.C.C. slab type bridges are economical in the medium span range of 8 to 15 meters. These frames have high stability against lateral forces such as wind and earthquake.

 

2. ACCORDING TO THE TYPE OF SUPERSTRUCTURE

1. Arch Bridges,

2. Suspension Bridges,

3. Truss Bridges,

4. Steel Rigid Frame Bridges and

5. Cantilever Bridges

 

3. ACCORDING TO THE RELATIVE POSITION OF THE BRIDGE FLOOR

1. Deck Bridge

Deck Bridge is one in which the track is carried on the top of the superstructure spanning member. It is constructed where the depth of the superstructure is small and sufficient Head Room is available. Examples: Masonry Arched Bridges and Railway Bridges.

2. Through Bridge

In this type, the track is carried at the bottom of the superstructure. Examples: Suspension Bridges and Bow-string Girder Bridges.

3. Semi-through Bridge

In this, the roadway is carried at some intermediate level between the deck and through type bridge. That is, the flooring is supported at some intermediate level of the superstructure.

 

4. ACCORDING TO THE PURPOSE or FUNCTION SERVED

1. Highway Bridge

2. Railway Bridges

3. Foot Bridges

The Foot Bridge is a bridge exclusively used for carrying pedestrians, cycles and animals.

 

5. ACCORDING TO THE ALIGNMENT or INCLINATION

1. Straight or Square Bridges

These bridges are constructed at right angles to the axis of the river i.e., direction of flow of water. This type of crossing is known as Square Crossing and hence the name Square Bridge.

2. Skew Bridges

These are bridges which are constructed not at right angles, but at some other angle to the axis of the river i.e., direction of flow of water. Skew bridges are not recommended, because construction of skew shape is very difficult; Foundation of the skew bridge may get scoured.

 

6. ACCORDING TO THE POSITION OF HIGH FLOOD LEVEL (H.F.L.)

1. Submersible Bridge

Submersible Bridge is constructed in unimportant routes so as to reduce the construction cost. It allows the highest flood to flow over its superstructure, submersing the communication route. Hence, the name is Submersible Bridge. Flood water flows during monsoon only for a short period of the year. During the rest of the year, there may be no flow or normal flow runs under the bridge. Example: Cause Way.

2. Non-Submersible Bridge

It carries the roadway above H.F.L. of the river. It is meant for carrying un-obstructed traffic throughout the year. It always allows the highest flood water to flow under the superstructure of the bridge.

 

7. ACCORDING TO THE LOADING

1. Class AA Bridges

2. Class A Bridges

3. Class B Bridges

 

8. ACCORDING TO THE SPAN LENGTH

1. Culverts [Culverts are explained later.]

2. Minor Bridge,

3. Major Bridge and

4. Long Span Bridge

 

9. ACCORDING TO THE LIFE

1. Permanent Bridges

Permanent Bridges are bridges constructed at very high cost. They have a very long life of the order of a few centuries. Examples: R.C.C. Bridges, Steel Bridges, etc.

2. Temporary Bridges

Temporary Bridges are bridges constructed at a low cost. They have a very limited life. They are constructed during the construction of permanent bridges or during major repair work of permanent bridges. Temporary bridges are disassembled after the permanent bridges are constructed or repaired. Example: Timber Bridges.

 

10. ACCORDING TO THE INTER-SPAN RELATIONSHIP

1. Simple Bridges

Simple Bridges include all beam, girder or truss bridges supported at both the ends. They are suitable for spans up to 8 meters.

2. Continuous Bridges

Bridges which continue over two or more spans are known as Continuous Bridges. They are used for large spans and where unyielding foundations are available. [Continuous Bridges are explained later.]

3. Cantilever Bridges

Bridges which are fixed at one end and free at the other are called Cantilever Bridges. They can be used for spans varying from 8 meters to 20 meters. [Cantilever Bridges are explained later.]

 

11. ACCORDING TO THE LEVEL OF CROSSING

1. Over Bridge

Over Bridge is a bridge constructed to enable one form of land communication over the other and hence the name Over Bridge.

2. Under Bridge

Under Bridge is a bridge constructed to enable a road to pass under another communication route (railway) or obstruction and hence the name Under Bridge.

 

12. ACCORDING TO THE METHOD OF PROVIDING CLEARANCE IN NAVIGATION CHANNELS

1. Movable Bridge [The Movable Bridge is explained later.), 2. Transporter Bridge