# R and D Coefficients For Seismic Force-Resisting Systems

Building load-bearing system selection,

*Carrier System Behavior Coefficient R*and*Strength Excess Coefficient D*are under user control.

Using the TBDY 2018 Wizard, the necessary instructions are made to the user.

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.

**Notation**

**D =** Resistance Surplus Coefficient **I =** Building Priority Coefficient **M _{DEV} =** Tipping moment arising from earthquake loads at the base of the reinforced concrete wall or braced frame

**M**Total tipping moment at the base from earthquake loads for the whole building

_{o}=**R =**Structural System Behavior Coefficient

**4.3.2. R and D Coefficients According to Carrier System Type**

**4.3.2.1 -** Cast in-situ and precast concrete, steel, mild steel, masonry, wood building structural systems and **4.3.3** 't defined for various ductility **Annex 4** , as defined in *the Structural Behavior Factor R* and *Resistance Redundancy Factor D ***Table 4.1** ' is also given.

**4.3.2.2 - In** composite column systems, *R* and *D* coefficients given for steel structural systems shall be used.

According to the definition given in **4.3.2.3 - 3.3.1** , in buildings with externally rigid walls surrounded by basements, (R / I) = 2.5 and D = 1.5 in the lower part of the basement floors.

**4.3.2.4 -** If one of the two conditions defined in **(a)** and **(b)** below cannot be **met in** any direction, in buildings with reinforced concrete curtain **walls** and / or steel braced frames with DTS = 1, 1a, 2, 2a, the * Structural System Behavior Coefficient in* that direction Instead of

*, (4/5) R will be considered. No change will be made in the*

**R***Strength Excess Coefficient D.*

**The**tie-beam curtain system satisfying the conditions given in

**4.5.4.5**will be considered as a single curtain.

**(a) In the** structural system, the base overturning moment M _{DEV} taken by a single wall or steel braced frame shall not be more than 1/3 of the total base overturning moment M _{o} resulting from the earthquake loads for the whole building in that direction .

**(b)** Construction each side axles located screen / screen or steel braced frame / receives base overturning moment of the frames M _{DEV} or M _{DEV} 'the sum of all, that the direction in total floor tilting moment occurring in seismic loads for the entire building M _{o} ' s 1 It will not be less than / 6.