Foundation is the lower portion of the building usually located below ground level, which transmits the loads of the super structure to the supporting soil. A foundation is therefore that part of the structure which is in direct contact with the ground to which loads are transmitted.
Functions of Foundation
1. Reduction of load intensity
Foundation distributes the loads of the super structure, to a larger area so that the intensity of the load at its base (i.e. total load divided by the total area) does not exceed the safe bearing capacity of the sub-soil.
2. Even distribution of load
Foundations distribute the non-uniform load of the super structure evenly to the sub soil. For example, two columns carrying unequal loads can have a combined footing which may transmit the load to sub soil evenly with uniform soil pressure. Due to this, unequal or differential settlements are minimized.
3. Provision of level surface
Foundation provide leveled and hard surface over which the super structure can be built.
4. Lateral stability
It anchors the super structure to the ground, thus imparting lateral stability to the super structure. The stability of the building, against sliding and overturning, due to horizontal forces (such as wind, earthquake etc.) is increased due to foundations.
5. Safety against undermining
It provides the structural safety against undermining or scouring due to burrowing animals and flood water.
6. Protection against soil movements
Special foundation measures prevents or minimizes the distress (or cracks) in the super structure, due to expansion or contraction of the sub soil because of moisture movement in some problematic soils.