Scale factors for response spectrum and time history curves

[AleksaBgd94]

Hi everyone,

I use Response Spectrum function from Eurocode in SAP2000 for my project. Should I use scale factor 9,81 when defining the response spectrum load, because response spectrum curve is defined as a fraction of graviotanal acceleration?

Also,if I import time history function from file (accelaration is in m/s2 and time is in s), do I have to use any scale factor when defining linear time history load case?

Units used in both cases are kN,m,C.

I appreciate your help

 

[Erik Panos Kostson]

Not familiar with SAP2000 (except that Strand7 the software I use can import SAP2000 models), but it seems that the response spectra is typically normalised with g (grav.), thus one would need to multiply it, set a scale factor, in order to get the correct acceleration.

See these two posts for more details: Link

[link extras.springer.com/2001/978-1-4613-5640-0/SapTutor.pdf]Link[/url]

If you have a time history in acceleration units and not normalised units, then I suppose it does not need to be multiplied with anything.

 

[JoshPlumSE]

From the SAP2000 help file:
"A response-spectrum function is simply a list of period versus spectral-acceleration values. In SAP2000, the acceleration values in the function are assumed to be normalized; that is, the functions themselves are not assumed to have units. Instead, the units are associated with a scale factor that multiplies the function and that is specified when the response-spectrum load case is defined."

Therefore, I believe you would enter a 9.81 scale factor when the response spectrum load case is defined.

 

[AleksaBgd94]

I agree with you.

Thank you