DESIGN AND ANALYSIS OF THE DIFFERENT TYPES OF THE FOUNDATIONS

The foundations are Structural elements that transfer load to the earth .If these loads are to be properly transmitted, foundation must be designed to prevent excessive settlement. The choice of the foundation to be used in a given situation depends on the bearing capacity of the soil, type of structure , type of loads , permissible differential settlement and economy .The choice is usually made from experience but it is advisable to carry out a comparative study of the different Designs to determine the suitable economical foundation. The size of foundation depends upon the permissible bearing capacity of the soil.Total load per unit area under the footing must be less than the permissible bearing capacity of the soil to prevent excessive settlement.In general foundations have to resist vertical loads , horizontal loads and moments.For the purpose of design of the foundation,values of density , bearing capacity , coefficient of internal friction of the soil are required to Design the foundation.These data must be known accurately, reasonably prior to the design of footing. Two terms are used to know the bearing capacity ie the Gross bearing capacity and the net bearing capacity.The depth of foundation is governed to secure the safe bearing capacity,as required to penetrate below the zone where seasonal weather changes are likely to cause significant movement due to swelling and shrinkage of soils .Hard rocks , granite,trap and diorite have been assessed 3300 kN /sq mt and sand stone and lime stone 1650 kN / sq mt ,broken bed rocks considered 900 kN / sq mt and the soft rock 450 kN / sq mt of the net safe bearing capacity.IS:1080 --1962 may give more clarifications to the relevant choice and experience required for the different Designs of the most economical foundations .