Document: NUREG-0800
Document ID: b5a87a6e-5e73-493f-b8d9-5de2b5feba56
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070317.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
as described above. When an appropriate recorded or specified time history is not available as input motion for seismic system analysis, an artificial time history (three components) may be generated from the design response spectra for the purpose of carrying out a time history analysis. The response spectra obtained from such an artificial time history of motion should generally envelop the design response spectra for all damping values to be used. The procedures used to generate response spectra are reviewed. In addition to the comparison of the response spectra derived from the time history with the design response spectra, the frequency intervals at which the spectral values are calculated are also reviewed. 3.7.1-3 DRAFT Rev. 3 - April 1996 When time history analyses are performed, either of the following options may be considered. In either case the time histories may be real or artificial. Option 1: Single Time History Use of single time history is justified by satisfying a target power spectral density (PSD) requirement in addition to the design response spectra enveloping requirements. Option 2: Multiple Time Histories In lieu of the use of a single time history, multiple artificial or real time histories may be used for analyses and design of structures, systems, and components SSCs . The number 8 and adequacy of time histories with respect to design response spectra are reviewed. In some instances, a nonlinear analysis of the structures, systems, and components SSCs9 may be appropriate (e.g., the evaluation of existing structures). Multiple time history analyses incorporating real earthquake time histories are appropriate when such analyses are proposed. The adequacy of time histories used in the analyses is reviewed. 2. Percentage of Critical Damping Values The percentage of critical damping values used for Category Istructures, systems, and components SSCs is reviewed for both the OBE and the SSE. Critical damping is the 10 amount of damping that