What is a combined footing used for?

Combined footing is used while construction of two or more columns when they are close to each other and their foundations overlap. The main purpose of using combined footing is to distribute uniform pressure under the footing.

What are the situations in which combined footings are preferred?

This type of footing is preferred when only single column is appearing in the foundation plan of a particular project. Combined footing: Combined footing supports two or more column loads. These may be continuous with rectangular or trapezoidal in plan.

What are the type of combined footing?

Types of Combined Footing The combined footing may be rectangular, trapezoidal or Tee-shaped in plan. Rectangular footing is provided when one of the projections of the footing is restricted or the width of the footing is restricted.

Why top reinforcement is provided in combined footing?

No its not necessary to provide top reinforcement for Isolated footings, unless footing is under tension. If footing goes under tension, then you have to provide tension reinf accordingly. However, some engineer’s do provide very minimum reinf at top just to avoid shrinakge cracks at top of footing.

Which are the design principles of combined foundation?

A combined footing runs between two or more columns and obviates the need to have multiple isolated footings placed at each column location. Combined footings help to resolve applied stresses throughout the footing and hence have greater stability and can carry significantly more stresses into the ground.

How many types of combined footings are possible?

How many types of combined footing are possible? Explanation: Combined footing is provided when 2 columns are very close by. They can be rectangular or trapezoidal in section. Explanation: CPRF uses the combination of pile and raft foundation as the name suggests.

Why raft foundation is used?

Raft foundation is generally used to support structures like residential or commercial buildings where soil condition is poor, storage tanks, silos, foundations for heavy industrial equipment etc.

What are the design principles of combined foundations?

What is the necessity to provide combined rectangular footing?

Combined footing for two columns become essential when the heavily loaded column is near the property line or when there is some restriction on the total length of the footing. or when one column carries heavy load compared to others.

What is a combined footing design?

Combined Footing Design When two or more columns are supported in a row and a common foundation is called combined footing. The point of application locates the column loads. Such that the pressure of allowable soil does not exceed when computing the area of the footing.

What is a trapezoidal combined footing?

A trapezoidal combined footing is considered 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. They can not make an equal rectangular footing because there is come an unequal load from the structure.

When to use strap-beam type combined footings?

Strap-beam type combined footing is used when one column is located on a property line, resulting in is an eccentric load on a portion of the footing. Therefore provide a beam in the footing to the adjacent column footing to restrain the overturning effect. This type of footing is provided under the following situations: 1.

What is the function of footings in construction?

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.