Damping of Pipe for EQ calculation

ROHR2 Dynamic calculations, questions and discussions
ROHR2stoss - Structural Analysis with Dynamic Loads using Direct Integration
Beiträge: 135
Registriert: Mi 14. Sep 2011, 10:18

Damping of Pipe for EQ calculation

Beitrag von r2user » Mi 13. Mär 2013, 10:20

Hi Rohr2support

I have a question about modal response seismic calculation.
For a project the floor response spectra were given for 2% damping but I should consider 5% damping for the piping system.
How can I modify the damping in the earthquake calculation?
My superposition method for the Eigenvalues is SRSS but Rohr2 only allows to modify the damping for CQC method.

Best regards

Rohr2 User

Beiträge: 393
Registriert: Mi 14. Sep 2011, 08:23

Re: Damping of Pipe for EQ calculation

Beitrag von rohr2support » Do 14. Mär 2013, 12:53

Hi Rohr2 User

For the calculation seismic analysis using modal response method you need to enter the floor response spectra (FRS)
for all support points of your piping system which are corresponding to the damping of the piping system.
ROHR2 has no way of calculating a new FRS for a different damping as the underlying model of the building is not
part of your system.

The damping value that you enter for CQC method, should be the same as the one used for your FRS which is the assumed
damping of your piping system. This value cannot be used to modify the FRS (e.g. change the damping of the FRS).
On the other hand the CQC method need the damping value to determine a distance value in therms of frequency between
neighbouring modes.

Best regards

Rohr2 Support


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