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.


D = Resistance Excess Coefficient
I = Building Importance Factor
R = Structural System Behavior Coefficient
R a ( T ) = Seismic Load Reduction Coefficient depending on the predicted ductility capacity and period
T = Natural vibration period [s]
T B = Horizontal elastic design acceleration spectrum corner period [s]

4.2.1. Earthquake Load Reduction Coefficient - 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 . - 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: