Online Manuals RFEM 6 / RSTAB 9 | Concrete Foundations

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2024-07-11

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Add-on Concrete Foundations

External Stability - Geotechnical Checks

Tables for concrete foundations

User-defined values for allowable soil stress

For this type of design, the existing soil pressure is compared to the specified allowable soil stress.

Determination of the stresses in the soil joint and the load eccentricities

The design shear force with additional foundation loads V_z,+add as well as the resulting design bending moments M_y,+add and M_x,+add in the foundation base are required to determine the eccentricity of the effective vertical loads:

e_{x} = - \frac{M_{y, + a d d}}{V_{z, + a d d}}

e_{y} = \frac{M_{x, + a d d}}{V_{z, + a d d}}

Eccentricity of Effective Vertical Load in x- and y-Direction

Determining the Effective Foundation Area

The ground failure analysis only considers a part of the actually available foundation base - the part where the resulting axial force acts in the middle.

L^{'} = L - 2 \cdot |e_{x}|

B^{'} = B - 2 \cdot |e_{y}|

A^{'} = B^{'} \cdot L^{'}

Effective Base Area

Existing Soil Pressure

With this, you can determine the existing soil pressure:

σ_{v o r h} = \frac{{V^{'}}_{d}}{A^{'}}

Design Value of Ground Failure Action

Design check

The existing soil pressure is compared to the specified soil pressure:

η = \frac{{V^{'}}_{d} / A^{'}}{{R^{'}}_{d} / A^{'}} \leq 1, 0

Design Criterion of Ground Failure

Parent Chapter

Ground Failure