Why we provide Foundations or Footings?
In simple words, Consider 1m3 of concrete weight i.e., 2400 Kgs to 2600 Kgs depending on mix. Think for a Two storeyed building how much concrete needed? How much quantity of bars needed? to construct a building. Foundation is to be strong enough to bear that all loads without any settlement, So for spreading the vertical load to large area footings are constructed.
What Is Combined Footing?
Combined footings are constructed for two or more columns when they are close to each other and their foundations overlap. Design of combined footings with example is discussed. The function of a footing or a foundation is to transmit the load form the structure to the underlying soil.
Design of Combined Footing Excel Sheet A footing when used for two columns or more than two columns is called combined footing. The combined footing is mainly two types: Rectangular Combined Footing Trapezoidal Combined Footing. Combined footings Combined footings are provided to support two or more column loads. These may be continuous with rectangular or trapezoidal. A Combined footing is used to support the load of two or more adjacent columns. To have a uniform bearing pressure and to minimize differential settlement between columns.
Combined footings become necessary under the following circumstances:
when the isolated footings overlap.
when the exterior column is close to the property line with the result symmetrical isolated footing cannot be provided.
if there is required two or more columns construed in a small area then we can use combined footing.
Another advantage of combined footing is where the load-bearing capacity of the soil is low there we construed combined footing. Where the soil capacity of the Construction area is unequal to distribute the load evenly to the sub-soil we construed combined footing. This is another advantage of combined footing. The common advantage of combined footing is when a column closes the property line and footing is not spread the front of the property line then combined footing help to construct the column.
Application of Combined Footing:
When two columns are very close enough to each other such that their footing overlap. When the load-bearing capacity of the soil is low, the requirement of more area under the individual footing.