By using the coefficients obtained from the map by the program, the spectrum curve given in Figure 11.4-1 with Equation 11.4-3 - 11.4-3 is automatically obtained.
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
T = Natural vibration period [s]
T0 =Horizontal elastic design acceleration spectrum corner period [s]
TS = Horizontal elastic design acceleration spectrum corner period [s]
TL = Transition period to constant displacement region in horizontal elastic design spectrum [s]
Sa = Horizontal elastic design spectral acceleration [ g]
Horizontal elastic design spectral accelerations Sa, which are the ordinates of the horizontal elastic design spectrum for any earthquake ground motion level considered, are defined in terms of the gravitational [ g ] depending on the natural vibration period.
With the spectral response acceleration parameters obtained from USGS depending on the coordinates, horizontal elastic design spectrum Sa is calculated according to the formula below . It is represented by a total of 4 functions, different in each region, or the horizontal elastic design spectrum. It’s shown in the graph below.
It’s calculated with the equation 11.4-5 from T=0 to T0 .
It’s equal SDS from T0 to Ts .
It’s calculated with the equation 11.4-6 from Ts to TL .
It’s calculated with the equation 11.4-7 for periods greater than TL.
In the Analysis Settings Wizard - Design Spectrums tab, the horizontal design spectrum is calculated and graphed by using the design spectral response acceleration parameters determined with online and offline options depending on the coordinates.
In Analysis Settings Wizard - Design Spectrums tab, horizontal design spectrum is calculated by using design spectral acceleration coefficients determined with online and offline options depending on the coordinates and its graph is created automatically.
Due to the need for site-specific analysis for site class F, the calculation is not made in the above way. The reduced design spectrum needs to be imported as a .txt file.
Example