Under what condition we made the choice of foundation?

to choose the foundation to provide a strenghtened strata below the ground to transfer the great amount of dead and live load of the super structure. 

 The resistance of the soil. It is important to make a good reconnaissance soil 

- The type of structure to found, therefore the loads applied to the foundation (different charges for a detached house and a tower)

To answer this question it is necessary to define the various types of foundations and determine their properties so that we can determine the appropriate type of foundation where the (safe & economic costs).

It is determined to be a two-pronged key start racing in determining the foundations: -First: it must be determined loads of the building on columns, and it comes from the structural design of the building in addition to the number of flats, many factors affected the loads dimension columns from each other and the structural system of the building.Second: soil report to determine the properties of these soils and bearing capacity on different depths.

After that are determined loads resulting from the structural analysis of the building and after determining the quality of soils and their properties and bearing capacity at different depths of the soil report.

We will now explain the types of foundations are to determine their suitability with the results we have them already.

First: shallow foundations: the foundations that are working on a few depths ranging from 1.5 - 3.0 meters approx.1. Isolate foundations: the foundations are made for each column is below its own base.2. Combine foundations: a foundation that is one foot for the column of two or more.3. Strap foundations: the foundations are made in the form of a linear at the bottom walls.4. Foundations raft: It is the foundation that is being done to most of the building columns and entrusted to be one basis for all of the building columns.

Second: deep foundations: the foundations that are working at great depths up to 60 meters depth and is called Piles.1. Anchor piles: a pile that is the depth of its work until they reach solid ground that can Thama loads them.2. Friction piles: a pile that is calculated frictional resistance has to be based on the length of the design loads.3. Mixed piles: it is combining between the anchor &friction at the same time.This is a preliminary identification of any quality of foundations (shallow foundations or deep foundations), depending on the quality of the soil and the type of building and the loads on.Example 1: If there is a skyscraper large number of roles over 100 role it leads to the existence of very large loads, which requires the work of deep foundations to reach the layer of earth that can bear these loads.Example 2: If there is a normal traditional building consisting of four floors, for example, it would be appropriate to build on the foundations of shallow soil work report.

In the end, I should like to point out that there are two main factors to determine the optimal type of foundations: -1. Technically a disciplinary what privatize his full safely according to the safety requirements without exaggeration.2. From the economic foundations of the work you turn from carrying the building but without prejudice to the security or increase the security of the proportion of all specifications.

Final I hope to answer your question

Soil Bearing capacity & type of soil

No. of floors & columns loads

seismic zone

size of footing from design

          1- type of foundation soil and underground layers 

2- columns reactions

3- design code

4- type of building

5- wind loads

6- earthquake loads

7- owner requests

8-  design requires

Foundations are selected according to the type of building and design style and bearing capacity of the soil

we are considers are type of soil, type of building that is means load of building 

The choice of foundation type depends on:

- The type of structure to found, therefore the loads applied to the foundation (different charges for a detached house and a tower)

- The resistance of the soil. It is important to make a good reconnaissance soil.

. If the surface layer is strong enough, it will still be necessary to make a

ground reconnaissance in the foundation level to a depth of twice the width of the

foundation and ensure that the layers underneath are fairly resistant.

. If the surface layer is not strong enough, a soil survey will be made on

a greater depth. We always choose the most economical foundation. by Prof. Amar KASSOUL

I agree with the answers above

Soil Bearing capacity & type of soil

Columns Load 

Size of foundation