What is Foundation And Types Of Foundation

What is Foundation And Types Of Foundation:

What Is Foundation

Generally Foundation can be defined as the lowest load-bearing part of a building, typically below ground level.

Foundation in building is used to transfer loads below the soil.It is used to transfer gravity loads to the earth.

What Is Foundation

How to make a Foundation 

To make a foundation, we normally dig a trench in the ground, digging deeper and deeper until we come to subsoil, which is more solid than the topsoil that is used to grow plants and crops. When the trench is deep enough, we fill it with any strong, hard material we can find. Sometimes we pour in concrete into the trench, which we strengthen even more by first putting long thin round pieces of steel into the trench. When the concrete dries, the steel acts like the bones in our body to tie the foundation together. We call this reinforced concrete.

Once the foundation has been packed down tightly, or dried hard, we can begin to build the building superstructure.

Uses and Objectives Of Foundations

• To distribute the load of the structure over a large bearing area.
• To load the bearing surface at uniform rate so as to avoid unequal settlement.
• To prevent the lateral movement of the supporting material.
• To increase the stability of the structure as a whole.

Types Of Foundations:

Foundations are of different types and the type of foundation is selected based on the suitability and type of soil conditions at the site.

Below are the Types of Foundations in Civil Engineering

Foundations are mainly classified into two types.

They are

1.Shallow Foundations

2.Deep Foundations

What is Shallow Foundation

Shallow Foundations are those foundations where Depth of foundation is less than width.(D

Types Of Shallow Foundations:

1.Combined Footing

2.Isolated Footing

3.Cantilever Footing

4.Mat Footing/Foundation

Types Of Foundations and their uses:

1.Combined Footing

Combined footings are used when columns are closely spaced and the soil having low bearing capacity.They are made common for two or more columns.They are rectangular or trapezoidal in shape.

2.Isolated Footing

Isolated Footing is also known as Column Footing.Column footing is in the form of flat slab and may be constructed through plain or reinforced concrete.They are used for depths greater than 1.5 meters.

3.Cantilever Footing

Cantilever footings are also called as STRAP Footings.When an edge footing cannot be extended beyond the property line the edge footing is linked up with the other interior footing by means of a strap beam. Such footings are called as strap footings.

4.Mat Foundation

Mat foundation is also known as Raft Foundation.Mat Foundation spread across the entire area of building.This type of foundations are used to support heavy structural heavy loads from walls and columns.

These type of foundations are used in expansive soils where bearing capacity of soil is less.They are used to prevent differential settlements on footings.This type of footing is preferred generally when one-half area of the structure is covered with individual footings and wall footings is provided.

Mat Foundations should not be used where ground water table is above the bearing surface of soil which causes Liquefaction.  

What Is Deep Foundation

Deep foundations are those where depth is greater than its breadth.They transmits the load of super structure to hard rock strata below vertically.

Types Of Deep Foundations

1.Pile Foundation

2.Spread Footing

3.Well Foundation

1.Pile Foundation

Pile Foundations are adopted in loose soils with lesser SBC (Safe Bearing Capacity Of Soil).

Pile Foundation is a deep foundation which is used to transfer heavy loads from building and structure to hard strata of soil.These type of foundations are used to prevent uplift pressure due to seismic and wind forces.

Pile Foundations uses pile caps to transfer loads and to hold the piles driven below the ground.

What is Pile Cap

pile caps are used to transfer loads and to hold the piles driven below the ground.Center of gravity of piles and centroid of pile cap shall coincide.

Main Types Of Pile caps used in Pile Foundation

a)Circular

b)Square

c)Rectangular

4)octagonal

Minimum spacing of piles is 2.5 to 3 times of pile diameter.Pile foundations resists the loads by skin friction by using end bearing piles.

2.Spread Footings

A shallow foundation is a type of foundation which transfers building loads to the earth very near the surface, rather than to a subsurface layer or a range of depths as does a deep foundation.

Spread Footings are generally used for individual columns.They are used in buildings mainly.Spread footings are those whose base is more wider than a typical load bearing wall foundations.

Spread Footings are also known as wall footings.

3.Well Foundations

Well Foundation is also known as Caisson Foundation.These are very expensive foundations and are used only in major construction works.Well foundation are suitable when the soil contains large boulders obstructing the penetration during installation of pier or pile foundations.They are used to resist heavy vertical and horizontal loads and are used in the construction of large water front structures as pump houses.

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