What is Spread footing Foundation | Types, Designs, Advantages

Hello everyone, we are introducing a new topic, what is spread footing foundation . Today we will answer your all questions related to spread footing and many more. I hope you must get satisfaction by visiting our site. In this article, we are exactly going to discuss foundation also.

As you all know to stand properly in our life we need a strong foundation, just like that if you are constructing a building then you also need to give a very strong foundation to that structure. Now we will give more information below, so keep reading.

What is foundation?

Foundation means base. When we start constructing a building, we need to dig a certain foundation in the ground to give strength to that building. Actually, if we want to give an exact definition of foundation then it may be like this, after digging the ground we create a base or foundation.

The lowest part of the structure or building is situated at the bottom of the earth, and it is connected to the soil directly. So that the structure or any building can stand properly in it. It is called a foundation. The entire weight of the building is borne by the soil which lies on the ground.

How many types of foundations?

There are two types of Foundations.

  1. Shallow Foundation
  2. Deep Foundation

Shallow Foundation

When we make a foundation while constructing a building we can see if the width of the foundation is bigger or equal to its depth. Then you can understand that there is going to happen a Shallow foundation. This type of foundation is made to bear the light weighted structures.

There are so many types of shallow foundations. We are going to discuss some of them listed below.

  1. Spread footing or Isolated footing.
  2. Mat or Raft footing.
  3. Strap footing or Cantilever footing or wall footing.
  4. Combined footing.
  5. Grillage footing.
types of spread footing
What is spread footing all about spread footing

What is Spread footing or Isolated footing?

As you know that here we telling you about spread footing, which is a part of shallow foundation. In such a type of spread footing, we need to widen the lowest part of the foundation. Which touches to ground level. In this footing, the particular load of the structure extends to a large area. Which is called spread footing.

There are various kinds of Isolated Spread footings are following.

  • Stepped footing for wall
  • Wall footing without steps      
  • Slopped footing for a column        
  • Single pad footing                                  
  • Stepped footing for a column.

What is Mat or Raft footing?

Generally, raft or mat footing is used where pile foundation can’t be done. As well as when the weight of the building is very bulky then mat footing is needed. It looks like Mat. In this footing, iron steels are stretched vertically and horizontally. We use this type of footing at the place where the bearing capacity of the soil is not sufficient. We do this because the load of the structure will depend entirely on this foundation.

Various types of mat footing.

  • Piled raft
  • Two-way beam and slab
  • Plate with pedestal
  • Rigid frame mat
  • Flat plate mat
  • Plate thickened under column

What is Strap footing or Cantilever footing or wall footing?

Strap footing is the design of joint footing. On two different bases with one horizontal column, two different columns are interconnected with each other. In such type of footings, the equal load of the structure goes to the soil.

What is combined footing

When the soil tolerance level is very less than we use Combined footing. In such types of footing, there can be 2 or more columns on the same base. According to the weight of the building structure, we use many columns in combined footing. This types of footing consist of columns at the same distance. Actually, they are located nearly to each other.

Different types of Combined footing.

  • Rectangular combined footing 
  • Trapezoidal combined footing

What is Grillage Footing

There are more than one or two layers of beams in the Grillage footing. We use such types of footing when we construct a heavy building or structure. Grillage footing is made of concrete, which is situated from the outside. In which beams are created like steps. All load of the structure is bear upon this footing. When Soil doesn’t bear the complete load of the structure. Then All load goes upon the footing.

Different types of Grillage footing.

  • Steel grillage footing 
  • Timber grillage footing

Deep Foundation

This is another type of foundation in which the foundation depth is bigger than its foundation width. So you can understand that such types of foundations are called Deep foundations.

There are so many types of Deep foundations. We are going to discuss some of them which are listed below.

  1. Pile foundation
  2. Basements
  3. Drilled Shaft foundation
  4. Caissons
  5. Buoyancy rafts

What is pile foundation?

The pile foundation is an important part of a deep foundation. This type of foundation is made of concrete or steel. If you are getting construction work done in an area where the soil has less bearing capacity, then it would be appropriate to have a pile foundation. In a pile foundation, all the pillars construct very closely. Their job is to send the structure’s load to the ground in equal quantity.

What is Basement Foundation?

The basement is the lowest part of any building and is made for living or keeping things. On the other hand, we can use this only for storage. By making a basement, we can make full use of our land. The basement is hot in winter and it is cool in summer. Generally, basements call underground rooms sometimes.

Drilled shaft foundation?

By drilling in the ground deeply to provide a strong base for any structure Drilled shaft foundation is done. A drill shaft foundation uses to construct heavy buildings. This type of foundation transfers the load of the structure equal to the ground.

What is Caissons or well foundation?

If a contractor is going to construct any bridge or structure underwater then The Cassion foundation is done. In such places where the upper layer of soil is not so useful, but the lower layer of the soil is very hard then we use the Cassion foundation here. The pillars of this foundation are made of RCC columns. In the Cassion foundation, blank cylinders of steel are used. In which concrete fills.

What is a Buoyancy raft foundation/ balancing raft foundation/ floating foundation?

As you hear the name of the foundation which is floating foundation, it doesn’t mean that it flows or swims on water. When we use this type of foundation to build a structure then firstly we dig some layer of soil from the ground. We make a base for the structure.

After completing the structure, the weight of the soil which is excavated and the weight of the structure will be same. Then the structure will stand properly. Therefore it is also called a balancing raft foundation. This is completely scientific. This theory is given by Archimedes in science.

What are the advantages of spread footing?

There are many advantages of spread footing.

  • This type of footing is very easy to do.
  • Spread footing can be constructed in various shapes like circles, rectangular, squares, etc.
  • By using this footing Structure weight can extend in a large area.
  • It can be the best and most affordable choice.
  • For constructing this type of footing either you can use a specialist or common constructor.
  • Although its construction is easy so there are very fewer chances of failure with this type of footing.

The design of spread footing

Here is the design procedure of spread footing.

  1. First of all, find the load and member size of the structure on the level of the foundation.
  2. After that, there is a need to collect information about geotechnical and then set factual and interpretive data on measure footing.
  3. When geotechnical data sets. Then set the depth and place of the total foundation materials.
  4. Now it turns to check the bearing capacity of the soil. After knowing this you can decide which type of footing needs there.
  5. Check effects at 2B depth.
  6. Choose the best footing materials like concrete, steel, aggregate, sand, etc.
  7. Find the necessary dimensions of footing.
  8. Set the thickness (T).
  9. After that set the sizes, number, and spacing of the reinforcing bars.
  10. Make a connection or design between the foundation and the structure.
  11. Now you have to check the sliding possibility of the structure.

Formula of spread footing calculation?

To determine the area of spread footing which is located at the bottom.

A = QT/q

Where QT means Quart. (A total load of structure bearing on spread footing)

q‘ stands for the base area of spread footing.

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We have discussed a lot of things about footing and foundation. In this article, you can get many ideas about spread footing. You can increase your knowledge about different types of foundations.

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