These footings spread the super-imposed load of wall or column over a larger area. Spread footings support either a column or wall. Spread footings can be in the form of
Single footing The figure 3 shows a single footing for a column, in which the loaded area bxb of the column has been spread to the size BxB through a single spread. The base is made of concrete.
Stepped footing The figure 4 below shows the stepped footing for a heavily loaded column, which requires greater spread. The base of column is made of concrete. Usually masonry walls have stepped footing
Sloped footing The figure 5 below shows the case in which the concrete base does not have uniform thickness, but is made sloped, with greater thickness at its junction with the column and smaller thickness at the ends.
Wall footing without steps The figure 6 shows the spread footing for a wall, consisting of concrete base without any steps.
Stepped footing for walls Usually, masonry walls have stepped footings as shown in figure 7. It has concrete base.
Grillage Foundation The figure 8 below shows a steel grillage foundation for a steel stanchions carrying heavy load. It is a special type of isolated footing generally provided for heavily loaded steel stanchions and used in those locations where bearing capacity of the soil is poor. The depth of such a foundation is limited to 1 to 1.5m. The load of the stanchion is distributed or spread to a very large area by means of two or more tiers of rolled steel joints, each layer being laid at right angles to the layer below it. Both the tiers of the joists are then embedded in cement concrete to keep the joists in position and to prevent their corrosion.
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