Most Important Types Of Foundation
Foundation is an important part that transfer load from the structure to the ground. It connects to the ground. The building stands depend upon the foundation.
Importance of Foundation
1. It can distribute the weight of the structure to the soil.
2. It avoids settlement which is not equal.
3. It is also able to reduce the lateral movement of the structure.
4. It also increases stability of the structure.
Various Types of Footing
There are different kind of foundation available. Foundation is depended on the profile, size of soil, load of the structure. Foundation is divided into two types. One is shallow foundation and another one is deep foundation.
If the depth of the foundation is lesser than the width that is called shallow foundation.
Isolated Spread Footing
This is very popular type of shallow foundation. This foundation is also very affordable. This is used to spread and convey concentrated burdens by the columns or the pillars. This are basically used to make ordinary building. This foundation transfers the load directly from the column to the soil.
This shape of isolated spread foundation may be rectangular, square or roundabout. It can be compromised by both the reinforced or non-reinforced material. It is unacceptable for the orientation of large loads. To get the size of the footing readers have to divided the total load at the column base by the bearing capacity of the soil.
Many types of spread footing are mentioned below:
1. Single pad footing
2. Stepped footing for a column
3. Wall footing without step
4. Grillage foundation.
This type of footing is used for distributing the structural loads or non-structural load bearing walls to the ground. The width of the wall footing is 2 to 3 times the width of the wall. Stone, brick and reinforced concrete are used to construct the wall foundation. This type of footing is very affordable when the loads are transmitted in small magnitude and it is also placed on dense sand and gravel.
Combined footing is provided when the columns of the structure are placed, or low bearing capacity of the soil and overlapping footing of them. There are different types of combined footing available. These are
1. Slab type
2. Slab and beam type
3. Rectangular type
4. Raft type
5. Strap beam type.
Combined foundation is very cheap when
A.) The columns of the structure are placed close to each other.
B.) The dimension of one side of footing is very restricted to lower value.
Strap footing and combined footing are quite similar. The foundation under the columns is built and connected by a strap beam in strap footing.
This type of foundation is used only there where other types of shallow or pile foundation is not suitable. The load of structure is distributed over a large area. In raft foundation reinforced concrete slab is placed over the whole area of the structure. In this type of foundation, the whole area of basement floor slab behaves like foundation. This foundation is called raft because the building floats on a sea of soil.
If the width of the foundation is smaller than the depth of the foundation it is called deep foundation.
This type of foundation is used to reduce cost, transmit loads to soil strata. There is various type of pile foundation available based on the function, material and construction method.
Based on function:
1. Sheet piles
2. Load bearing piles
3. End bearing piles
4. Friction piles
5. Soil compactor piles.
Based on the material and construction method.
1. Timber piles
2. Concrete piles
3. Steel piles.
This type of foundation is an underground structure. It is able to transit more loads. This type of foundation shallower than pile foundation. It is utilized in multi-story structure. It is a cylindrical structural member. It also transfers heavy loads from the superstructure to the soil by end bearing. This type of foundation can transfer the loads only by bearing.
This is very affordable when
1. A heavy load is transferred to the soil.
2. Sound rock strata lie under the decomposed rock layer at the top.
This type of foundation is a watertight retaining structure. It is used as a bridge pier, construction of dam. This type of structure is mainly used in required structure where foundation beneath a river or similar water bodies. Different type of caisson foundation is mentioned below.
1. Box Caisson.
2. Floating Caisson.
3. Pneumatic Caisson.
4. Open Caisson.
5. Sheeted Caisson.
6. Excavated Caisson.
This type of foundation is economic when
1. The pile cap is required to be minimized.
2. Noise and vibration have to be reduced.
There is different type of Caisson foundation available based on the function, material and construction method.