Horizontal Elastic Design Spectrum.
Symbols
F_{S }= shortperiod site coefficient
F_{1} = longperiod site coefficient (at 1.0s period)
S_{DS} = Shortperiod design spectral acceleration coefficient [dimensionless]
S_{D1} = Design spectral acceleration coefficient for a period of 1.0 second [dimensionless]
S_{S }= mapped spectral response acceleration parameter at short periods
S_{1} = mapped spectral response acceleration parameter at a period of 1 s
T = the fundamental period of the structure, s
T_{A} = Horizontal elastic design acceleration spectrum characteristic period
T_{B} = Horizontal elastic design acceleration spectrum characteristic period
T_{L} = longperiod transition period
S_{ae(T)} = Horizontal elastic design spectral response acceleration [g]
The map spectral acceleration coefficients S_{s }and S_{1 }values of the coordinates, specified at Building Geometry and Location, were obtained from the AFAD earthquake map data using the Analysis Wizard online option.
According to the ZA local soil class specified in the geotechnical report, local soil effect coefficients are obtained from TBDY 2018 Table 2.1, and ideCAD Structural automatically calculates the design spectral acceleration coefficients.
S_{s}  0.706 
S_{1}  0.205 
F_{s}  0.8 
F_{1}  0.8 
S_{DS} 

S_{D1} 

T_{A} 

T_{B} 

The horizontal elastic design spectral accelerations S_{ae}(T), which are the ordinates of the horizontal elastic design acceleration spectrum for any earthquake ground motion level considered, are defined in terms of gravitational acceleration [g] depending on the natural vibration period.
Based on the coordinates, the spectral acceleration coefficients obtained from AFAD and the horizontal elastic design spectrum S_{ae}(T) are determined according to the formula below. For the horizontal elastic design spectrum, it is represented by a total of 4 functions, different in each region, is shown in the graph below.
The horizontal elastic design spectrum is created with the “TBDY 2018 Wizard for Analysis Settings” command using spectrum values specified above.
The horizontal elastic design spectrum created in the “Analysis Settings” window is shown below.