Document: NUREG-0800
Document ID: 585516eb-af20-45dc-a470-9638ec9381f3
Document Type: srp
Title: Each calculated spectrum of the artificial time history is considered to envelop
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640306.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.0
CFR Part: 
CFR Title: 

Content:
response spectra (FIRS) and are derived as free-field outcrop spectra; that is, only the effects of materials that are below the base elevation of the seismic Category I structure are included in the site response analysis. For each seismic Category I structure foundation, if the CSDRS-consistent spectra at the foundation level envelop the site- specific FIRS at the foundation level, the standard design is acceptable for that site, assuming no other issue is identified during the review process. If not, then proceed to step vii. vii. Perform an SSI analysis using the site-specific FIRS and an advanced seismic analytical technique (e.g., method that considers the effects of incoherent ground motion). When such analytical methods are utilized, the detailed technical justification shall be reviewed on a case-by-case basis. Further discussion on consideration of the effects of incoherent ground motion is provided in subsection II.4.C (under the heading Input Ground Motion, Specific Guidelines for SSI Analysis) in SRP Section 3.7.2. The in-structure responses in terms of floor response spectra, building member forces, and deformations at key locations in the structure shall be obtained. The key locations for calculating the in- structure responses, proposed by the licensee, need to be evaluated to ensure that they are sufficient to represent the various locations throughout the building. Locations should include responses at peripheral locations to detect rocking and torsion, and should include responses to check overturning, torsional, and sliding stability of the structures. The dynamic models and analysis techniques need to be sufficiently refined to be able to capture the response of the structures throughout the frequency range of interest, including the high frequency responses, typically expected in the central and eastern United States (CEUS) regions. The SSI analysis shall also consider the site-specific soil variability (i.e., best estimate, lower bound