# Internal Force Corresponding to Brittle Behavior (4.3.5.3)

The reduced internal forces corresponding to the non-ductile behavior are automatically increased by the D coefficient selected from

**Table 4.1**.

**Symbols**

**D =** Strength Redundancy Coefficient **R =** Structural System Behavior Coefficient

For reduced internal forces corresponding to the non-ductile behavior of the structural system elements, the Strength Excess Coefficient will be used as the multiplier (D> 1). These internal forces are internal forces that cause brittle collapse, such as shear force in reinforced concrete elements and forces acting on joints in steel elements.

However, in structural systems with high ductility level, the internal forces increased by D coefficients are not taken greater than the internal forces compatible with the yield state at the (allowed) sections defined as a requirement of the principle of capacity design.

For example, in a reinforced concrete column, the shear forces caused by earthquake effects are obtained by dipping with the Strength Excess Coefficient D. Since the shear force shows brittle collapse behavior , internal forces caused by earthquake effects must be multiplied by the Strength Excess Coefficient D according to **4.3.5.3** .

In structural systems with high ductility level , the internal forces increased by the * D* coefficient cannot be taken higher than the internal forces compatible with the yield state defined based on the principle of capacity design. If we give the same reinforced concrete column example , the

*Shear Safety of Columns*described in

**TBDY Section 7.3.7**is an example of this situation. The design shear forces calculated in this section are internal forces compatible with the yield state of the columns defined based on the principle of capacity design. Therefore

**Section 7.3.7 TBDY**described in above "the sum of D calculated from seismic shear enhanced with vertical loads,

**Eq. (7.9)**If calculated with Ve is less than Ve, this shear force will be used instead of Ve. " statement is compatible with this principle.