QUANTITY OF MATERIALS FOR TRAPEZOIDAL FOOTING BY CIVIL GURUJI
Channel: Civil Engineers Training Institute
Date: 2020-07-23

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Foundations provide the structure's stability from the ground:

To distribute the weight of the structure over a large area in order to avoid overloading the underlying soil (possibly causing unequal settlement).
To anchor the structure against natural forces including earthquakes, floods, frost heaves, tornadoes and wind.
To provide a level surface for construction.
To anchor the structure deeply into the ground, increasing its stability and preventing overloading
The design and the construction of a well-performing foundation must possess some basic requirements that must not be ignored. They are:

The design and the construction of the foundation is done such that it can sustain as well as transmit the dead and the imposed loads to the soil. This transfer has to be carried out without resulting in any form of settlement that can result in any form of stability issues for the structure.
Differential settlements can be avoided by having a rigid base for the foundation. These issues are more pronounced in areas where the superimposed loads are not uniform in nature.
Based on the soil and area it is recommended to have a deeper foundation so that it can guard any form of damage or distress. These are mainly caused due to the problem of shrinkage and swelling because of temperature changes.
The location of the foundation chosen must be an area that is not affected or influenced by future works or factor
Shallow foundations, often called footings, are usually embedded about a metre or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock.

Another common type of shallow foundation is the slab-on-grade foundation where the weight of the structure is transferred to the soil through a concrete slab placed at the surface. Slab-on-grade foundations can be reinforced mat slabs, which range from 25 cm to several meters thick, depending on the size of the building, or post-tensioned slabs, which are typically at least 20 cm for houses, and thicker for heavier structures.

Deep foundations
Main article: Deep foundation
A deep foundation is used to transfer the load of a structure down through the upper weak layer of topsoil to the stronger layer of subsoil below. There are different types of deep footings including impact driven piles, drilled shafts, caissons, helical piles, geo-piers and earth stabilized columns. The naming conventions for different types of footings vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete