# Response Modification Coefficient (R)

The earthquake load reduction coefficient R _{a} (T) is determined automatically by **Equation 4.1a** and **4.1b** .

R and D coefficients in the equations are under user control.

R and D coefficients selected by the user in the analysis settings wizard and report results are checked automatically. R and D coefficients that do not comply with

**TBDY**are not allowed.

**ICONS**

* D =* Resistance Excess Coefficient

**I =****Building Importance Factor**

*Structural System Behavior Coefficient*

**R =**

**R**_{a}**(**

**T****Seismic Load Reduction Coefficient depending on the predicted ductility capacity and period**

_{ }) =

**T =****Natural vibration period [s]**

**T****Horizontal elastic design acceleration spectrum corner period [s]**

_{B }=**4.2.1. Earthquake Load Reduction Coefficient **

**4.2.1.1 -** Within the framework of *Design Based on Resistance* , the definition of the *predicted ductility capacity - strength demand* relationship and the *earthquake load coefficients* determined accordingly are given in **ANNEX 4A** .

**4.2.1.2 -** According to the definition made in **ANNEX 4A** , the *Earthquake Load Reduction Coefficient to* be taken as basis in reducing linear elastic earthquake loads is defined as follows:

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