Damping in Response Spectrum Analysis

[shino10121012]

Hey Guys,
I understand that during the analysis the response spectrum function will automatically adjust to cater for modal damping when the spectrum is defined as per a particular code that is built in.

https://wiki.csiamerica.com/display/kb/Damping+in+response-spectrum+analysis

I would like to know if I will be able to input different spectra corresponding to various damping values through an input file so that modal damping can be done.

 

[Shz713]

Just make user-defined function within SAP2K or import using text file, it's same as you define time history load function.

Shoot for the Moon, even if U miss, U still land among Stars!

 

[stressed]

Every response spectrum function that you define can have its own damping ratio

 

[shino10121012]

Thank you @Shz713 and @stressed for your response.

But i think you guys are not clear with my query. What i wanted to know was if i could linearly interpolate between the two input response spectra that i have defined to get the required accelaration for a damping equal to the modal damping.

For Ex. I define a RespFunc1 corresponding to damping 5% and RespFunc2 corresponding to 10%. Now due to different materials used in the structure I m ending up with a modal damping of say 7%. So the acceleration that i need to consider is of a damping value of 7%. So will SAP consider the damping corresponding to 7% by any chance? or will I end up with a response acceleration corresponding to 5% (or10%) only.

NB : I am a frequent user of STAADPRO and there is a provision in it where i can input two spectrum for two different damping values and ask the solver to consider a linear interpolation between the input spectra.