# How do you calculate combined footings?

## How do you calculate combined footings?

Steps for Design of Combined Footing

1. Locate the point of application of the column loads on the footing.
2. Proportion the footing such that the resultant of loads passes through the center of footing.
3. Compute the area of footing such that the allowable soil pressure is not exceeded.

What is combined footing?

When two or three columns are located very near to each other, we provide a single substructure for them and the footing is known as a combined footing. A combined footing may be rectangle or trapezoidal in plan. The object is to get uniform pressure distribution under the footing.

What are the shapes of the combined footing?

A combined footing is a long footing supporting two or more columns in (typically two) one row. 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 combined footing is provided?

The main purpose of using combined footing is to distribute uniform pressure under the footing. Hence, this is done so that the center of gravity of the footing area should be equal to the center of gravity of the two columns.

How is the depth of combined footing governed?

Hence, the depth of the footing is governed by one-way shear.

What are the disadvantages of combined footing?

In combined footing, it is difficult to maintain the center of gravity of the columns. The general disadvantage of combined footing is that its size should be varied to the place. Sometimes it’s should be made rectangular or sometimes trapezoidal.

#### What is inverted arch footing?

An Inverted Arch Footing is a civil engineering structure in the form of a modified arch, inverted in comparison with a standard arch footing. Like flying arches, the Inverted Arch Footing is not used to support the load, such as a bridge, but rather to withstand sideways internal loads.

When and where combined footing is provided?

Combined footings are provided when distance between two columns is small and soil bearing capacity of soil is lower and their footings overlap with each other.

What are the types of combined footing?

Rectangular Combined Footing. This footing is used when two columns carry equal loads.

• Trapezoidal Combined 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
• Strap footing.
• Raft Footing.
• ## What is spread Foundation?

By Paul Cartmell. The term “spread foundations” is commonly used to refer to shallow foundations that are too closely positioned to allow a slab foundation to be installed beneath a building.

What is column footing details?

▐ A column is a vertical structural member designed to transfer a compressive load.

• Shape Columns can be classified according to their cross sectional shape. Common column shapes include:
• Elements of classical columns The base is the lowest part or division of a column.
• ▐ Footings are an important part of foundation construction.