The footings which are provided below the column independently are called isolated footings. This type of footing may be square, rectangular or circular in section.
Isolated footing consists of a thick slab that may be flat or sloped or stepped.
Isolated or single footings are used to support single columns. This is one of the most economical types of footings and is used when columns are spaced at relatively long distances.
Its function is to spread the column load to the soil so that the stress intensity is reduced.
The objective of the Design of isolated Footings is to Determine:
- Area of footing
- Thickness of footing
- Reinforcement Details of footing with a satisfying moment and shear force consideration.
- Check for development length and shearing stresses
All these things carried out with considering the loads on footings. Safe bearing capacity (SBC) of the soil, Grade of concrete and steel. Minimum cover to main reinforcement shall not be less than 50mm on the
surface of the contact with the earth face. The diameter of main reinforement shall not be less than 10mm.
The Important purpose of foundation are as follows;
- To transfer forces from superstructure to firm soil below.
- To distribute stresses evenly on foundation soil such that foundation soil neither fails nor experiences excessive settlement.
- To develop an anchor for stability against overturning.
- To provide an even surface for smooth construction of superstructure.
Due to the loads and soil pressure, footings develop Bending moments and shear forces.
Calculations are made as per the guidelines suggested in IS 456 2000 to resist the internal froces.