Concrete below base plate is simulated by Winkler subsoil with uniform stiffness, which provides the contact stresses. The average stress at the bearing area used for compressive check.

## Concrete in bearing

User can choose between local bearing capacity check of reinforced concrete pad (GB 50010, Equation 6.6.1-1) and plain concrete pad (GB 50010, Equation D.5.1-1).

#### Reinforced concrete pad

\[ F_l \le F_c = 1.35 \beta_c \beta_l f_c A_{ln} \]

#### Plain concrete pad

\[ F_l \le F_c = \omega \beta_l f_{cc} A_l \]

where:

*F*_{l}– compressive force*F*_{c}– compressive resistance*β*_{c}– strength influential coefficient of concrete;*β*_{c}= 1 for concrete grade up to C50,*β*_{c}= 0.8 for concrete grade C80; linear interpolation is used for concrete grade between C50 and C80- \( \beta_l = \sqrt{\frac{A_b}{A_l}} \) – concentration factor
*A*_{b}– concrete supporting surface which is concentric to*A*_{l}*A*_{l}– base plate area in contact with concrete surface*A*_{ln}– area*A*_{l}with subtracted holes in base plate for anchors*f*_{c}– design compressive strength of concrete; GB50010, Table 4.1.4-1*f*_{cc}= 0.85*f*_{c}– design compressive strength of plain concrete; GB50010, Table 4.1.4-1*ω*– compression load distribution factor;*ω*= 0.75 for uneven load distribution,*ω*= 1.0 for even load distribution

## Transfer of shear

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

- Friction between base plate and concrete / grout
- Shear lug
- Anchor bolts

### Anchors

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

Anchors are not checked in the software.