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C_d = Deflection amplification factor
R = Response modification coefficient
I_e = Importance factor
δ_xe = Deflection

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Deflection Amplification Factor, C_d, is defined in Table 12.2-1.

The application of the factor R/I_e to the design response spectrum reduces not only design forces but also displacements. To compensate for this, ASCE 7 requires that the deflections at level x at the center of mass, δ_x, be determined in accordance with where C_d is from Table 12.2-1, I_e and δ_xe. Using a value C_d equal to R would result in the displacement δ_x being equal to δ_xe, which would be consistent with the equal displacement rule.

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