Foundation is a structural supporting member which transfer loads from the Building’s walls or Columns to the Earth. The loads from slab, beam, column, wall etc. should be safely transferred to the Soil. The substructure that is provided to transfer loads from the superstructure to the earth is known as a foundation.
Courtesy - 123 rf
There are many different types of foundation that can be used to build your house. It is difficult to select the right one for your house. Choices of the foundation will depend on many factors like the closeness of the tree, drain and stability of slope etc.
Must Read: What is Isolated Footings?
Apart from the above the following factors also affect the choice of the foundation:-
01. Importance of the Building:
The more the importance of building, the better foundation system is needed.
02. Life of the Structure:
when a life envisages is more, you need a foundation system without problem for the temporary structure we can take a risk.
03. No. of Storeys:
The higher the no of storeys, the stronger the foundation is needed.
04. Loads from the Structure:
The First factor considered is loads from the structure. A Combination of Dead loads and live loads on the buildings, Other loads like wind loads, snow loads, earthquake loads etc. are also considered based on their location.
05. Materials of Constructions:
Selection of material for construction such as steel, masonry, and concrete construction also affect the foundation.
06. Types of Adjoining Structure:
Selection of foundation for building construction also depends on the neighbouring structures. If adjoining structure foundations are very nearer to the boundary line it does affect the foundation type.
07. Types of Foundations:
Different types of foundation such as wall footings, combined footings, raft footings, combined footings, isolated footings, strip footings etc, Based on types of soil and loads from the structure.
08. Water Table Level:
Foundation system will also depend on the depth of water table. Foundation should rest either on fully dry soil or wet soil. But a layer when alternate drying and wetting occurs should be avoided.
09. Location of Building:
Location of building with respect to natural disaster zones like the earthquake, cyclone, flood, volcano. The foundation will be designed considering whether the building is situated in a locality which is highly prone to earthquake, cyclone, flood etc. special provision will have to be made for them.
10. Type of Soils:
Different types of soils such as sandy soil, loose soil, clayey soil or expansive soils etc. The soil nearer to the soil surface is called topsoil and 300 mm depth from the surface is called as subsoil. These subsoils are used for the foundation for small buildings.
Soil investigation should be carried out to know water table level, type of soil, nature of the soil, depth of different layers of soil and to know the safe bearing capacity of the soil at the different levels.
When the load is transferred from the structure to the soil through the foundation, the soil tends to consolidate the soil resulting settlement of foundation system. The settlement of foundation cause cracks in structure or structure can even collapse in case of large settlement.
Thus the right choice of foundation type is the most important judgment that the structural engineer has to face.