HOW TO CHOOSE CORRECT FOUNDATION FOR YOUR CONSTRUCTION?

HOW TO CHOOSE CORRECT FOUNDATION FOR YOUR CONSTRUCTION

A Foundation is a lower portion of building structure that transfers its gravity loads to the earth. Foundations are generally broken into two categories:

1.  Shallow Foundations (3m depth)

2.  Deep Foundations. (20 – 65m depth)

BY MATERIAL:

1.  Brick footings

2.  Stone footings

3.  PCC (Plain Cement Concrete) footings.

4.  RCC (Reinforced cement concrete) footings

BY SHAPES:

1.  Square footing

2.  Rectangular footing

3.  Circular footing

4.  Continuous footings.

When the concrete dries on foundations the steel acts like the bones in our body to tie the foundation together

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Know Difference Between Footings And Foundations:

The Footings is part of the foundations, which is constructed of concrete or brickwork masonry and is used as a base for floor columns and floor walls.

The main function of the foot is to transfer the vertical loads directly to the soil. The term foot is commonly used in conjunction with the superficial foundation.

Know Where We should Provide Shallow foundation & Deep foundation?

Foundations may be shallow or deep foundations depending upon the load and type of foundation soil.

If the load to be supported is very high and the soil is of low bearing capacity, Deep foundations are provided.

If the soil has adequate bearing capacity at reasonable depth then shallow footings are provided.

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Before choosing the correct foundation you should know the types of footings used

A shallow foundation is typically 20 metre in depth.

This types of Foundation mostly built for lightweight buildings where the condition of the soil is extremely good with uniform layer and low water table.

Open Foundation or Spread Footings

Shallow foundations are also referred to as spread footprints or open foundations, as the earth is completely removed to construct mud feet and then filled with binoculars.


This is referred to as spread footing because the base is wider than the load-bearing wall.

Types of Shallow Foundation

Individual Footings Or Isolated Footings

Shapes available

(Square, Rectangular, Circular, Continuous Spread, Combined & Ring Spread )

It is the most common type of base widely used for buildings. At this base, each column has its own base. These bases are connected with a socket beam just below ground level. It comes in various shapes, such as rectangular, circular, and continuous according to the load distribution.

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As a site engineer, you should have a slight idea on the area of footing should be constructed

Therefore,

Footing Area = Column Load / Safe Bearing Capacity.

Example: If the soil bearing capacity is 10 T/m2 (tonne/meter square) and the column has a vertical load of 10 T/m2 then the size of the 
footing will be 1 m2.

You can also design different geometric foundation shapes, such as circular, square, or rectangular. There are no limits. Also, you can find the safe bearing capacity of the soil in this method

Combined Footing

A footing which has more than one column is called as combined footing.  because the adjacent footing might be closer where shuttering is not possible

Shape available:

1.  Rectangular combined footing

2.  Trapezoidal combined footing

Strip Footings

Strip foundations are continuous footing which will be constructed at the load-bearing masonry construction where walls will be acted as a load-bearing structure.

The footing will be constructed continually under the walls to support the load developed on the walls. Greater the bearing capacity of soil lesser is the width of the Strip footing.

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These types of footings constructed in old masonry construction still these are in existence in local construction. And its Less durable when compared with other types of footings. This type of footing is not suitable for specific types of soils

Mat or Raft Foundation

Raft foundations (sometimes known as Mat Foundations) are a large concrete slab that can support a series of columns and walls. This type of foundation is mainly seen for the construction of tall residential buildings where it has a basement. The ratio of individual footings to total floor space is high.

When LCETED prefer to use Raft Foundation

it is used for large loads, which is why they are so common in the commercial building

The soil has a low bearing capacity so the weight of the building needs to be spread out over a large area to create a stable foundation

Typically if the footings would cover over half of the construction area then raft foundation would be used

If the walls of the building are so close that it would cause the individual footings to overlap, then raft foundations should be used

A Deep foundation is typically 20 metres to 60meter in depth.

Deep foundations mean, as the name implies, that foundations will be penetrated through the weak soil layer to great depth and supported on the strong soil layer or in the rock. Deep foundations compared to shallow foundations distribute the load of the superstructure vertically rather than laterally. Deep foundations are provided when the expected loads from the superstructure cannot be supported in shallow foundations.

The base will be larger than the shallow base (> 3m). Normally all deep foundations refer to us as foundations. But there are other types,

Types of Deep Foundation

Pile Foundations

Pile means the vertical member that will be penetrated through great depth. Since the function of the pile is to carry the load to the depths, there are different types depending on the construction methods and the materials used.

Normally all deep foundations refer to us as foundations. But there are other types,

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Caisson or Pier Foundation

Caisson or pier foundations are often used in large underwater construction bodies such as rivers, the sea. A box base also called a dock base is an airtight retention structure used as a bridge dock, in the construction of a concrete dam, or for boat repair.

Drilled Shaft Foundation

This type of foundation is used on bridges and large structures (subway train projects) where a long cylindrical shell is inserted and then poured with concrete along with reinforcement. Once the concrete hardens, the shape will be removed from the hole.

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