D = 1 is taken automatically in the calculation of the reduced internal forces corresponding to the high or limited ductile behavior of the structural system elements.
Symbols
D = Strength Redundancy Coefficient
R = Structural System Behavior Coefficient
The Strength Excess Coefficient is not used in calculating the reduced internal forces corresponding to the high or limited ductile behavior of the structural system elements .
Internal forces that oppose highly ductile or limited ductile behavior are bending moment, tensile force and similar internal forces. Ductility is the name given to the ability to make large changes or displacements without losing strength. Strength Excess Coefficient, D, is not used in reduced internal forces such as bending moment and axial force, which have ductile behavior.