 Map spectral response acceleration parameters SS and S1 are converted automatically to spectral response acceleration parameters SMS and SM1. Spectral response acceleration parameters SMS and SM1 are converted automatically to design earthquake spectral response acceleration parameters SDS and SD1.

Symbols

Fa = Short-Period Site Coefficient
Fv = Long-Period Site Coefficient for a period of 1.0 seconds
SMS = Short-period design spectral response acceleration parameter [dimensionless]
SM1 = Design spectral response acceleration parameter for a period of 1.0 seconds [dimensionless]
SS = the mapped MCER spectral response acceleration parameter at short periods as determined in accordance with Section 11.4.2,
S1 = the mapped MCER spectral response acceleration parameter at a period of 1 s as determined in accordance with Section 11.4.2
SD1 = Design spectral response acceleration parameter for a period of 1.0 seconds
SDS = Design earthquake spectral response acceleration parameters at short periods

Dimensional map spectral response acceleration parameters, risk-targeted maximum considered earthquake ground motion, for USA Earthquake Hazard Maps are defined under:

(a)   Short period map spectral response acceleration parameter SS

(b)  Map spectral response acceleration parameter S1 for a period of 1.0 seconds

The map spectral response acceleration parameters are determined by the map spectral response accelerations for 5% damping ratio. They are defined as dimensionless coefficients divided by the acceleration of gravity. For this reason, the equation described below is used to determine the effect of site soil coefficients while calculating under different soil conditions.

The map spectral response acceleration parameters SS and S1 are turned into the design spectral response acceleration parameters SMS and SM1 with eq. 11.4-1 and 11.4-2.

Wherein Fa and Fv defined below shows the local site coefficients.

Design earthquake spectral response acceleration parameters at short periods, SDS, and at 1-s periods, SD1, are determined from Eqs. (11.4-3) and (11.4-4).