# Stiffness Multipliers Usage in Accordance Table 4.2 (4.5.8)

The multiplier values given in Table 4.2 are automatically applied for the calculation of earthquake effects.

Both factors given in the table are taken into account in the calculation model. The effective cross-section stiffness factors are only applied to the calculations under the loads included in and under seismic load combinations.

Vertical loads indicated by G 'and Q' in earthquake combinations are also calculated once again with cracked section stiffness. And these loads are used in earthquake combinations.

The concept of effective section stiffness is based on the approximate linearization of the nonlinear internal force-deformation relationship (for example moment-curvature relation) up to flow in a reinforced concrete section in order to make linear elastic calculations. In the literature, the term cracked section stiffness is also used instead of the term effective section stiffness due to the cracking of concrete in the first stage in the context of nonlinear behavior in the bending effect.

### Modeling concrete cracked section properties for structural analysis:

The bending and axial l behavior in walls are changed by f11 or f22 depending on the direction of the local axis, and the shearing behavior is controlled by f12.

1-1 **d11: In** -plane axial stiffness (extension) occurring in the (X) axis

2-2 **d22: In** -plane axial stiffness (elongation) in the (Y) axis

1-2 **d12:** Stiffness resulting from the combination of "d11" and "d22" stiffnesses (transverse shortening)

3-3 **d33: In-** plane shear stiffness

4-4 **D11:** Out-of-plane bending stiffness around the (X) axis

5-5 **D22:** Out-of-plane bending stiffness around the (Y) axis

4-5 **D12: In** -plane shear stiffness resulting from the combination of D11 and D22 stiffnesses

6-6 **D33:** Torsional rigidity

7-7 **D44:** Out-of-plane shear stiffness in the (X) axis

8-8 **D55:** Out-of-plane shear stiffness in the (Y) axis

**Effective cross-section stiffness multipliers used for basement walls**

**D11:** 0.5 **D22:** 0.5 **D12:** 0.5 **D33:** 1 **D44:** 1 **D55:** 1

**d11:** 0.5 **d22:** 0.8 **d12:** 1 **d33:** 1

**Next Topic**