GENERAL NOTES ON THE DESIGN OF THE FOUNDATION (ISI)

The design of RCC footings and foundation is based on the assumption that the foundation is rigid so that the variation of pressure under the foundation will be linear .The distribution or pressure will be uniform if the centroid of the Footing coincides with the resultant of the applied loads .This conventional method holds good only in case of rigid foundation.Such an assumption becomes less and less accurate as the Footing become relatively more flexible.The requirements in design of foundation are (1) The pressure on the soil should not exceed the bearing capacity of the soil .(2) The settlement of the structure should be with in the permissible limits .Further there should be no differential settlement.Whenever the possibility of the differential settlement occures, the different portions of the structure should be made such as to settle independently of each other and where the bearing capacity of soil is low, RCC continues footings are provided and the footings shall be designed to sustain the applied loads, moments and forces and the induced reactions and to ensure that any settlement which may occur shall be as nearly uniform as possible and the safe bearing capacity of soil is not exceeded .In case of the sloped and stepped footings the effective cross section in compression shall be limited by the area above the nuetral plane and the angle of slope and the depth and location of steps shall be such that the design requirements are satisfied at every section sloped and stepped footings that are designed at a unit shall be constructed to assure action as a unit .