Bridges are an important infrastructural aspect of any location that serves the highly essential function of connecting two stretches of land, generally separated by a water body. Therefore, bridges must have a strong foundational base that can bear its load and help them serve their purpose to the best of their capabilities. An abutment is one such crucial element in the structure of a bridge. This foundational structure that holds up the entire bridge is important as it ensures stability and sturdiness. Read on to know more about abutment and its importance.
Types of abutment
Abutments in construction can be of several types. These largely include the following:
Gravity abutments
These abutments are used to transfer the weight of the structure resting on top of it vertically downwards. These are constructed of materials such as concrete or stone.
Cantilever abutments
These abutments are generally found in bridges and make use of a long beam known as the cantilever. These arm-like beams are projected from the structure to support the horizontal load without bending it.
Counterfort abutments
Counterfort abutments are used to support vertical loads. Like the arms of the cantilever, these have vertical ribs on the surface that oppose forces being applied horizontally.
Piled abutments
Piled abutments are used to set the structure deep in the ground in a way that the load is transferred to the stable geological layers of rocks and soil. Piles are the parts that are attached to the abutment to fix it securely into the ground.
Stub abutments
These are smaller abutments that are not meant for heavy-duty usage since they cannot reach much lower inside the ground’s surface. You can find these types of abutments in smaller bridges built on shallow foundations that are meant for lighter loads.
Semi-integrated abutments
These abutments are used in cases where aesthetic considerations are a priority since they can blend with the surrounding landscape.
See also: Steel for construction: What should you know?
Functions of abutment
Abutments serve some very important functions to ensure the stability of the structure. Following are its major functions:
Load transfer
The first and most important function of abutments is to transfer the load of the structure into the stable ground below so that it can sustain itself. The even distribution of the structure’s weight is necessary to avoid complications during the construction process such as settlements.
Stability and support
Abutments serve the function of protecting the structure against harsh external forces that might potentially cause it to weaken or collapse. These include pressure from forces like wind, water or geological elements.
Resistance to movement
Movement caused due to seismic activity, settlement or other factors might cause the structure to get deformed. Abutments help prevent this by resisting the motion and minimising its impact on the structure.
Alignment control
In the case of bridges, abutments help to fix the structure securely to the ground in a way that it remains straight. Proper and constant alignment of the bridge is crucial to ensure its safe usage.
See also: Construction of railway overbridges
FAQs
Where are abutments used?
Abutments are used to provide stability to large structures such as bridges, culverts, dams and tunnels.
Why is it important to use abutments?
Abutments ensure uniform load distribution of the structure so that it doesn't get deformed or yield to harsh external forces.
What is the difference between cantilever and counterfort abutments?
Cantilever abutments are used to resist vertical forces while counterfort abutments resist vertical forces.
Which is the most common type of abutment?
Gravity abutments are the most commonly used type of abutment.
Which abutment is suitable for lighter loads?
For lighter structures with shallow foundations, it is best to use stub abutments.
What is the advantage of using semi-integrated abutments?
Semi-integrated abutments seamlessly blend into the surrounding landscape without compromising the aesthetics of the structure.
How do abutments ensure the safety of the structure?
Abutments ensure the safety of the structure by even load distribution and resistance to environmental forces such as harsh weather and earthquakes.
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