| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | Modeling |
| Date Logged & Current Version | April. 2018 11.03.00.08 |
Problem:
How to evaluate the impacts of the SAM (Seismic Anchor Movement) combined with dynamic analysis with spectra.
In particular, it is requested the Complete Quadratic Combination (CQC Method).
Solution:
In general, AutoPIPE provides the capability of MSRS (Multiple Support Response Spectrum) analysis as per NRC guidelines which incorporates results from Seismic Anchor Movement. The results from internal only benchmark problems match closely with NRC supplied benchmark problems. AutoPIPE reference information for MSRS or ISM provides a summary of the procedures that we employ.
Modeling tips:for MSRS, Response Spectrum Analysis, and SAM analysis:
1. Try to capture frequency up to the input spectrum frequency range in your modal analysis.
2. Missing Mass option can be used to capture the response for the missing modes
3. CQC method is closer to SRSS, but at times can be lower or higher than SRSS method. CQC method tries to capture interaction of modes which are closely spaced
Example Model:
AutoPIPE Example model's folder has an MSRS Example Archive model named "MSRS EXAMPLE.APC" . Also see AutoPIPE MSRS Example1 file as part of the documentation explaining the same example model (Program Help > Bentley AutoPIPE > Supplemental Documentation > AutoPIPE MSRS Example 1).
References:
a. NUREG-32862: SEiemic Analysis of Piping Systems Subjected to Independent Support Excitation
b. NUREG 1061: Evaluation of other loads and load combinations
c. NUREG guide 1.92: Combinaing Modal Responses and Spatial Components in Seismic Response Analysis
d. EPR: Seismic Subsystems Analysis
Question #1:
Does the effect of S1 includes only the SAM and not the SPECTRA effects.
Answer #1:
Referring to page 7 of the MSRS Sample PDF:
For the MSRS analysis, the SAM case selection helps the user to be able to define / select the different support groups. If the SAM response (pseudo-static response) is required to be combined with SPECTRA (Dynamic Response), you will need to create a combination like S1 + R1 and combined them through SRS or ABS SUM method. So in that case you will have a user combination say MSRS1 (which will include S1 and R1 with combination method set to SRSS or ABS SUM). You can then have other user come combinations like GRTP1+MSRS1, which will take in to account both the SAM and SPETRA responses.
Question #2:
The default sequence consider is: gravity + temperature + pressure.
How the SAM and SPECTRA effects will be combined? The non-linearity will be taken into account?
Answer #2:
Non-Linear analysis and load sequencing is limited to Static Analysis Load cases. Dynamic and SAM analysis does not consider any load sequencing and non-linear support properties.
See Also
"Sam" (Seismic Anchor Analysis)