Document: NUREG-0800
Document ID: 1121c8ce-ab70-416c-9784-421014a1b25b
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1419/ML14198A460.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
nt safety, the use of the site-specific GMRS rather than the CSDRS is reviewed on a case-by-case basis in accordance with SRP Section 2.5.4. The free-field design response spectra (also referred to as the CSDRS for a DC) are usually developed for the 5 percent damping value. For the 3.7.1-10 Revision 4 – December 2014 case of RG 1.60 response spectra, Tables 1 and 2 of RG 1.60 provide amplification factors at four frequencies for calculating response spectra corresponding to different damping values. For the case of the free-field design response spectra that are different from RG 1.60 response spectra, procedures to calculate response spectra for different damping values other than 5 percent can utilize the latest available data/methods such as those in PEER Report 2012/01 or NUREG/CR-6728. The procedures used are reviewed by the staff on a case-by-case basis. To be acceptable, the seismic design response spectra should be specified for three mutually orthogonal directions - two horizontal and one vertical. Current practice is to assume that the design response spectra (including maximum ground accelerations) in the two horizontal directions are the same. B. Design Time Histories. The SSE and OBE design ground motion time histories can be either real time histories or artificial time histories. To be acceptable, the design ground motion time histories should consist of three mutually orthogonal directions - two horizontal and one vertical. For both horizontal and vertical input motions, either a single time history or multiple time histories can be used. When time histories are used, each of the three ground motion time histories should be shown to be statistically independent from the others. Each pair of time histories are considered to be statistically independent if the absolute value of their correlation coefficient does not exceed 0.16. Simply shifting the starting time of a given time history cannot be used to establish a different time history. When the