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Site Class and Site Coefficients

  • The floor type is chosen by the user.

  • Coordinate selection is made from the map.

  • If you use the online option, the spectrum coefficients from the AFAD map are processed online.

  • If you use the offline option, the spectrum coefficients in the program database are automatically processed.

Spectrum parameters are determined automatically using Equation 2.1.


F S = Local ground impact coefficient for the short-period region
F 1 = Local ground impact coefficient for a period of 1.0 seconds
S DS = Short-period design spectral acceleration coefficient [dimensionless]
S D1 = Design spectral acceleration coefficient for a period of 1.0 seconds [dimensionless]
S S = Short period map spectral acceleration coefficient [dimensionless]
S 1 = Map spectral acceleration coefficient for a period of 1.0 seconds [dimensionless]

Local Soil Impact Coefficients 

TBDY 2018 According to Table 16.1 , the average shear wave velocity ( V S30 ) , the average standard penetration impact number ( N 60 ) 30 or the average undrained shear strength ( c u ) 30 , depending on the ZA - It has been defined as six classes, ZF.

Depending on the local soil classes defined in TBDY 2018 16.4 , local soil impact coefficients F S and F 1 are given in Table 2.1 and Table 2.2 , respectively . Linear interpolation is performed for intermediate values ​​of map spectral acceleration coefficients in the tables. - Table 2.1 and / or Table 2.2 according to the ground entering the ZF site classes s AHAs specific soil behavior analysis must be performed.

In the Analysis Settings Wizard - Design Spectrums tab, design acceleration coefficients are obtained with the map spectral acceleration coefficients obtained depending on the coordinate with online and offline options. If the online option is used , acceleration coefficients are obtained from the AFAD Earthquake Hazard Map . In the offline option, the acceleration coefficients calculated over the program infrastructure are obtained. Both options give the same results.

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