How to evaluate the impacts of the SAM (Seismic Anchor Movement) combined with dynamic analysis with spectra. In particular, using Complete Quadratic Combination (CQC Method).
There are a number of references with details on Independent Support Motion and combinations methods.
BNL-NUREG--32862: Seismic Analysis of Piping systems subjected to ISE
NUREG-1061: Evaluation of other loads and load combinations
NUREG- 1.92: Combining Modal Response and Spatal components in seismic response analysis
In general, AutoPIPE provides the capability of MSRS (Multiple Support Response Spectrum) analysis as per NRC guidelines which incorporates results from Seismic Anchor Movement. We internally have benchmark problems, the results for which are matching closely with NRC supplied benchmark problems. AutoPIPE reference information for MSRS or ISM provides a summary of the procedures that we employ. In general, if you are not using MSRS, then your Response Spectrum Analysis, and SAM analysis would be two independent 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