Check of concrete block according to SP

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Concrete in compression

Concrete in compression under the base plate is checked according to SP 63.13330.2012, Cl. 8.1.44 – Calculation of reinforced concrete elements for local compression:

\[ N \le \psi R_{b,loc} A_{b,loc} \]


  • N – local compressive force from an external load
  • ψ – factor equal to 0.75 in case of non-uniform distribution of the local load across the bearing surface
  • Rb,loc = φb Rb – design compressive resistance of concrete in case of the local impact of compressive force
  • \( \varphi_b = 0.8 \sqrt{\frac{A_{b,max}}{A_{b,loc}}} \) and 1.0 ≤ φb ≤ 2.5 – concentration factor taking into account the triaxial stress in concrete
  • Rb = Rbn / γb – design value of concrete axial compressive resistance
  • Rbn – normative axial compressive resistance of concrete
  • γb = 1.3 – reliability factor for concrete under compression; editable in Code setup
  • Ab,loc – application area of the compressive force (bearing area surface) determined by finite element method as area in contact between base plate and concrete block
  • Ab,max – maximum design area established based on the following rules:
    • gravity centres of areas Ab,loc and Ab,max coincide
    • maximum design area is geometrically similar to application area; the slopes are 1 vertical to 2 horizontal.

Transfer of shear

The shear action at the base plate is assumed to be transferred from the column to the concrete foundation by:

  1. Friction between base plate and concrete / grout
  2. Shear lug
  3. Anchor bolts


The tensile forces in anchors include prying forces and are determined by finite element analysis.

Anchors are not checked in the software.

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