Classification of foundation

1) Shallow Foundation

B > D or

𝐵/D> 1

2) Deep Foundation

B ≤ D or 𝐵/𝐷≤ 1

Types of shallow Foundation

1) Concrete Pedestal Foundation

• This footing is provided for the columns containing very small external load.

• It is the most economical & basic type in which there is no need of 

Reinforcement.

• A min longidned R/F is provided without any lateral R/F.

• The Depth of this footing depends upon angle b/w the points of exterior edge 

of column & exterior edge of footing.

2) Isolated Footing

• This footing is provided for individual columns.

• This footing is provided when there is no limitation for space.

• This footing is provided for single shear ( one way shear & double shear (Two 

way punching shear)/

• The depth of footing is chucked along the moment generated along the footing 

from exterior edge of column.

3) combined footing

When the under to center distance b/w column in so small that there isolated 

footings overlap with each other. Then combined footing is provided.

• Combined Footing is designed such that the center of gravity of loads must 

coincide with center of gravity of footing.

• Combined Footing is designed in the form of rectangular continuo beam having 

+ve & -ve moments.

• There are 2 types of combined Footings:

i) Rectangular Footing

→ When there is no space limitation for length & width of footing.

ii) Trapezoidal footing

→ When there is space limitation of length or width of footing.

4) Mat/ Raft Footing

• It is a special case of combined footing in which all the columns of structure 

along both directions are provided with a common footing.

• It is provided in which the distance b/w columns is small & the safe bearing 

capacity of soil is law.

• When no. of columns in 1 row are provided with a common footing, the footing 

is known as footing.

• Combined footing, strip footing & mat footing are designed to centered 

differential settlement in structure due to column leads.

Deep Foundation

• This foundation is provided when load is very heavy & the condition of sail is 

not good at surface.

• This foundation is generally provided in the form of pile foundations.