The Constructor

Combined Footing Design with Example and Types of Combined Footing

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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. The choice of suitable type of footing depends on the depth at which the bearing strata lies, the soil condition and the type of superstructure.

Combined Footings

Whenever two or more columns in a straight line are carried on a single spread footing, it is called a combined footing. Isolated footings for each column are generally the economical. Combined footings are provided only when it is absolutely necessary, as
  1. When two columns are close together, causing overlap of adjacent isolated footings
  2. Where soil bearing capacity is low, causing overlap of adjacent isolated footings
  3. Proximity of building line or existing building or sewer, adjacent to a building column.

Types of Combined Footing

Rectangular combined footing

Steps for Design of Combined Footing

Detailing of Combined Footing

Detailing of steel (both longitudinal and transverse) in a combined footing is similar to that of conventional beam-SP-34. Detailing requirements of beams and slabs should be followed as appropriate-SP-34 See the Complete Design with an Example Read More: What is Punching Shear? Punching Shear in Slabs and Foundations Isolated Footing Design Example and Excel Sheet
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