# The Reduced Design Acceleration Spectrum for Horizontal Earthquake Forces

By using the parameters determined in **Table 12.2-1** and **11.5.1**, the Reduced Design Spectral acceleration, S_{a} is determined automatically according to **Section 12.9.1.2**.

According to the structural system type, using the R, C_{d} and Ω_{o} coefficients obtained from Table 12.2-1, * R/I_{e }*and the reduced design spectral acceleration are calculated automatically.

**Symbols**

* C_{d} = *Deflection amplification factor

*Seismic importance factor*

**I**_{e}=*Response modification coefficient*

**R =**The reduced design spectral acceleration * S_{a},* which is the ordinate of the reduced design acceleration spectrum for a given natural vibration period

*T*, used to determine the reduced seismic loads in the horizontal direction

*is that of*

**,***Design Response Spectrum., is obtained by dividing the*

**S**_{a}*Reduced Design Acceleration Spectrum for Modal Analysis and multiply with*

**R,****I**.

_{e}On the Analysis ASCE 7-16 Wizard - Design Spectra tab, the spectral acceleration coefficients obtained from USGB based on the coordinates and the horizontal elastic design spectrum * S_{a} *is calculated according to the formula below . Design Response Spectrum., it is represented by a total of 4 functions, different in each region, and shown with the graph below.

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