Before going to Ring Foundation, let me tell what is the foundation from the aspect of Civil Engineering.
Foundation: Foundations are structural elements that transfer loads from the building or individual columns to the earth. If these loads are to be properly transmitted, foundations must be designed to prevent excessive settlement or rotation, to minimize differential settlement and to provide adequate safety against sliding and overturning. A foundation is required for distributing loads of superstructure on a larger area such that soil below it does not fail in shear and settlement is within the safe limits. Foundations have to resist vertical load, horizontal load and moments. All structures are supported by suitable foundations. A foundation is, therefore, a connecting link between the structure proper and the ground which supports it.
Now let us jump to Ring Foundation.
Image Source: Google
The ring foundations are suitable and economical for symmetrical structures such as silos, cooling towers, smoke-stacks, transmission towers, radar stations, TV antennae, chimneys, bridge piers, underground stops, water towers, mine and liquid storage tanks, compared with the other geometrical shapes of the footings, such as (strip, rectangular, square and circular footings). The ring footings enable decreasing the amount of material used and cost of construction. Ring foundations are often adopted for large and tall structures to resist lateral loads and to increase the stability against overturning. In the design of ring foundations, very cmde simplifications have to be made. Therefore, developing a rational and practical procedure for estimating the bearing capacity of ring foundations is of great importance.
I hope you got some idea about it. Here I am adding few more pics which are results of some researchers performed on it.
When width= 0.76m and depth= 0.5m
SFD of 60 noded ring foundation:
BMD of 60 noded ring foundation:
Displacement of 60 noded ring foundation: