We all know that footing is an inseparable part of foundation construction. They are built by the help of concrete with rebar reinforcement. The objective of footing is to provide adequate support to the foundation and restrain settling. Footings are especially crucial in the areas where soil condition is not up to the mark.
In accordance with IS 6403 :1981 :
“Footing” is defined as a structure constructed in brickwork, masonry or concrete under the base of a wall or column for the purpose of distributing the load over a larger area.
In other word, footing is the bottommost part of a foundation. Footing and foundation are complimentary to each other.
A combined footing is a large footing which supports two or more columns in one row. It is basically rectangular or trapezoidal in shape.
Usage of Combined Footing
Construction practice may ordain using just one footing for two or more columns owing to:
1) Closeness of column (for instance around elevator shafts and escalators )
2) Owing to property line constraint, this may restrict the size of footings at boundary. The aberration of a column positioned on the verge of a footing may be made up by joining the footing to the interior column.