## Weighing structure

Key performance for the foundation is the maximum weight that it can effectively hold in the soil.That is why the calculation of the foundation begins with the determination of the total weight of the building.In order to establish what will be the load on the foundation, you must define the internal volume through the walls and the average density withdraw their total weight.This value is necessary to add a lot of overhead and intermediate floors and roofs.To the resulting weight is usually added from 20% safety margin.

## bearing capacity and soil

second important in determining not only the design features, but also the form of the foundation, is the type of soil on which it is installed, as well as depth.In other words -
bearing capacity of soil cushion, located directly under the foundation.Precise data on the density of soil and its bearing capacity and the presence of geological faults can only responsible geodesic after a series of laboratory tests.

## Determination of linear dimensions

In the case of a monolithic slab calculation is quite simple: the reinforcements must have a distance between them of at least 20 cm, and they must be covered with a layer of concrete is not thinner than 8-10 mm.Calculation of the strip foundation is much more difficult to perform, and the high accuracy in the calculation of self-worth and did not qualify.For this reason, the foundations satisfied with solid margin strength, avoiding the recommendations of project offices.

first design parameter - the width of the foundation, which varies depending on the bearing capacity of the soil.The first step is to set a minimum horizontal cross-sectional area of ​​the foundation having a thickness equal to the thickness of the walls.Typically, the ratio of width to height of the foundation is taken as 2: 3, based on this we can calculate the amount of concrete mass.Given that a cubic meter of solid concrete weighs 2400 kg, it is necessary to calculate the weight of the foundation, to add weight to his house and to check whether the value of the area of ​​support bearing capacity of soil.With a lack of base area must be increased accordingly linear dimensions of the foundation, and this leads to an increase of its mass, which also should be considered.

## density reinforcement

number of valves is determined by the following principle: in a cross section of the concrete structure cross-sectional area of ​​steel reinforcements should not be less than 0.1% of the total cross-sectional area of ​​the foundation tape that found p.7.3.5 SNIP 52-01-2003.This means that the linear dimensions of the tape 70h100sm area of ​​its cross-sectional area will be 700,000 square millimeters, so the cross section of reinforcement may be less than 700 square millimeters is not, which is approximately five to 14 mm steel rod with a periodic profile.