Well, this answer is easily available in any of the standard R.C.C and Geotechnical books, however, a basic introduction is provided here in this answer.
Foundation is the entire system while footing is just a part of the foundation system.
Footings are structural elements, which transfer loads to the soil from columns, walls, or lateral loads from earth retaining structures. In order to transfer these loads properly to the soil, footings must be designed to:
- Prevent excessive settlement
- Minimize differential settlement, and
- Provide adequate safety against overturning and sliding.
Broadly Foundation system is classified into 2 groups as per Terzaghi on the basis of Df/B ratio.
where Df= Depth of footing and B= Width of the Footing.
If Df/B=<1 - Shallow Foundation
If Df/B>1 - Deep Foundation
The following chart will detail out the further classification within Shallow and Deep Foundation.
Shallow Foundation: They are usually located not more than 1.2-2.0
meter below the lowest finished floor.
A shallow foundation system is generally used when
- The soil close to the ground surface has sufficient bearing capacity, and
- Underlying weaker strata do not result in undue settlement.
Shallow foundations are commonly used in most economical foundation systems.
I tried to provide a very basic understanding of the foundation system, you could explore (Design and Analysis) about it better from nptel lectures or any std. book.
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