Stress in the footing bottom

The stress in the footing bottom can be assumed as:

• rectangular (uniform in the footing bottom)
• general (trapezoidal) with different edge values

General distribution of stress follows from figure:

Stress in the footing bottom

where:

If in some points the stress becomes negative, the program continues with adjusted dimensions b*l while excluding tension from the analysis. Before computing the stress distribution due to surcharge the stress in the footing bottom is reduced by the geostatic stress in the following way:

There are three options in the program to specify the geostatic stress in the footing bottom:

• From the original ground
  It is therefore considered, whether the footing bottom in the open pit measured from the original ground is free of stress for the time less than needed for soil bulkage and subsequent loss of stress in the subsoil.
• From the finished grade
  The same assumptions as above apply.
• Not considered at all