ANGLE OF DISPERSION SHOULD NOT BE LESS THAN 45 DEGREE, AND THE FOOTINGS SHOULD ALSO BE CHECKED AGAINST THE PUNCHING SHEAR .

The angle of dispersion is confirmed 45 degree and it is assumed that load from a column or a wall spreads out in the form of a side slopes at an angle of 45 degree.There fore footings should lie with in a line drawn at 45 degree from the outer edge of the wall or column.For masonry foundation, the projection of any footing course should not exceed half the depth of the course . Usually each projection is taken a quarter length of the brick but not more than half brick and laid in the header courses with reference to the face of the wall .Where heavy loads from single columns are transmitted to a stratum of low bearing value ,the footings have to be extended much beyond the 45 degree line of load dispersion.Such foundations have to be of the form of a grillage ,raft or of reinforced concrete The footings or projections in this case are designed as cantilevers resisting an upward load equivalent to the pressure on the foundation.The moments to be resisted at the centre is equal to the moment of the resistance of the concrete at the footing and this formula applies to the masonry walls and columns which are not considered as rigidly fixed at the bottom with the foundation.The footing is also checked against the punching shear .Strip foundations on sloping sites should be on a horizontal bearing and stepped.At all changes of levels they should be lapped at the steps for a distance at least equal to the thickness of the foundation or twice the height of the step which ever is greater .The step should not be of greater heights than the thickness of the foundation.