Formula to calculate Sds(spectral response acceleration parameter at T=0.2sec ..)

[TheEverest]

I found dissimilarity to calculate Sds in Annex E. The formula given in the nomenclature and E.4.6.1-1 differ from each other, one formula uses Ss whereas the other uses S0. Can anyone please help me?

 

[HTURKAK]

I will suggest you to read E.4 Site Ground Motion ( E.4.1 thru E.4.6 ).

If you want a clear respond and If the subject tank is at site DEFINED BY ASCE 7 METHODS,pls share Site Class ( A to F), Ss and S1.

 

[TheEverest]

Thank you HTURKAK for your concern and quick reply. But I couldn't exactly find in E.4 about using Ss instead of S0. Can you please be more specific?

 

[HTURKAK]

[quote...... But I couldn't exactly find in E.4 about using Ss instead of S0. Can you please be more specific?][/quote]

Your question implies the site is located at ( SITES NOT DEFINED BY ASCE 7 METHODS ) and If no response spectra shape is prescribed and only the peak ground acceleration, SP

Ss = 2.5 SP

S1 = 1.25 SP


S0 =Mapped, maximum considered earthquake, 5% damped, spectral response acceleration parameter at a period of zero
seconds (peak ground acceleration for a rigid structure), %g ( this event return period is about 2500 years ) and (usually referred to as the peak ground acceleration). Unless otherwise specified or determined, S0 shall be defined as 0.4SS when using the mapped methods.

Q =Scaling factor from the MCE to the design level spectral accelerations ( the scaling factor to obtain associated with the event having a 10% probability of exceedance in 50 years. That is, recurrence interval of 475 years ); equals 2/3 for ASCE 7

SS = Mapped, maximum considered earthquake, 5% damped, spectral response acceleration parameter at short periods (0.2 sec), %g

These are all copy and paste from API 650 App.E and EC. I do not have any input. I also added the snap from App.EC which illustrates the notations.

In your case, pls be more specific.. Where is your site located when you look to E.4 ( E.4.1 thru E.4.3) ?..