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2024-07-11

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Concrete Foundations Add-on

Theoretical Principles

Design Specifications

Design Properties of Single Foundations

User-Defined Values for Allowable Soil Stress

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

Determination of Stresses in Soil Joint and Load Eccentricities

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

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

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

Eccentricity of Resulting Actions Including Additional Foundation Loads in x- and y-Direction

Determination of Effective Foundation Area

For the ground failure design, only part of the actual base area is taken into account—the part where the resulting axial force acts in the center.

L^{'} = m a x (w_{x} - 2 \cdot |e_{x}|; w_{y} - 2 \cdot |e_{y}|)

B^{'} = m i n (w_{x} - 2 \cdot |e_{x}|; w_{y} - 2 \cdot |e_{y}|)

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

Effective Foundation Length L', Foundation Width L', and Base A'

Existing Soil Pressure

This allows you to determine the existing soil pressure:

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

Design Value of Ground Failure Action

Design

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

η = \frac{{V^{'}}_{d} / A^{'}}{{R^{'}}_{d} / A^{'}} \leq 1.0

Design Criterion of Ground Failure

Parent Chapter

Ground Failure