Wednesday, October 17, 2012

Functions of Foundations.

Foundations serve the following purposes:

1. Reduction of load intensity. Foundations distribute 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. In the case of deep foundations, it transmits the super-imposed loads to the sub-soil both through side friction as well as through end bearing.

2. Even distribution of load. Foundations distribute the nonuniform load of the super-structure evenly to be 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 lo this, unequal or differential settlements are minimised.

3. Provision of level surface. Foundations provide levelled 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 buildlng, 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 minimises the distress (or cracks) in the super-structure, due to expansion or contraction of the sub-soil because of moisture movement in sorne problematic soils.

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