Document: NUREG-0800
Document ID: 0d1dd9a4-bcad-421f-a2f2-a33ef1c04988
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A223.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
ns. The UB high stiffness profile should make use of the LB damping properties for each layer of the profile. Similarly, the LB soft stiffness profile should make use of the higher damping properties. The profiles used should be consistent with those used in the PSHA evaluation, except that for those cases where backfill is used to replace unacceptable soils in the profile, the backfill properties should be used provided the backfill layers are shown to be extensive enough to be consistent with the one-dimensional free-field site response analyses. In addition, to ensure that the UB and LB profiles generated from the site-specific randomized set of profiles include an adequate range of variability, the layer velocities may need to be modified to ensure they possess the minimum coefficient of variation (COV) as discussed below under “Specific Guidelines for SSI Analysis.” iii. Using the FIRS as input to each of the deterministic soil profiles, the envelope of the computed response spectra at the ground surface should be shown to equal or exceed the mean spectra (PBSRS) at the surface at all frequencies of interest.