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:
ent response spectra (e.g., Regulatory Guide 1.60), the total duration of the artificial accelerogram should be long enough such that adequate representation of the Fourier components at low frequency is included in the time history. The total time duration between 10 seconds and 25 seconds is required to adequately match the design response spectra at 0.4 Hz. The corresponding stationary phase strong-motion duration should be between 6 seconds and 15 seconds. If site-specific information reviewed in SRP Section 2.5.2 indicates duration estimates outside the above ranges, the site-specific values should be used. The rationale for selecting lower and upper limits on duration is presented in NUREG/CR-5347 (Reference 610) . 31 For nonlinear problems, duration estimates are reviewed on a case-by-case basis. Option 1: Single Time History To be considered acceptable, the response spectra of the artificial time history to be used in the free field must envelop the free-field design response spectra for all damping values actually used in the response analysis. When spectral values are calculated from the artificial time history, the frequency intervals at which spectral values are determined are to be small enough such that DRAFT Rev. 3 - April 1996 3.7.1-6 any reduction in these intervals does not result in more than 10 percent change in the computed spectra. Table 3.7.1-1 provides an acceptable set of frequencies at which the response spectra may be calculated. Another acceptable method is to choose a set of frequencies such that each frequency is within 10 percent of the previous one. Table 3.7.1-1 Suggested Frequency Intervals for Calculation of Response Spectra Frequency Range Increment (hertz) (hertz) 0.2 - 3.0 0.10 3.0 - 3.6 0.15 3.6 - 5.0 0.20 5.0 - 8.0 0.25 8.0 - 15.0 0.50 15.0 - 18.0 1.0 18.0 - 22.0 2.0 22.0 - 34.0