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:
2.5.2 at low and high frequency and as presented in NUREG/CR-6728. The strong motion duration is defined as the time required for the Arias Intensity to rise from 3.7.1-11 Revision 4 – December 2014 5 percent to 75 percent. The uniformity of the growth of this Arias Intensity should be reviewed. The minimum acceptable strong motion duration should be six seconds. In addition to the duration for site-specific analysis, the ratios V/A and AD/V2 (A, V, D are PGA, peak ground velocity, and peak ground displacement, respectively) should be consistent with the characteristic values for the magnitude and distance of the appropriate controlling events defining the uniform hazard response spectra. These parameters should be consistent with the values determined for the low and high frequency events described in Appendix D of RG 1.208. For nonlinear structural analysis problems, multiple sets of ground motion time histories should be used to represent the design ground motion. Each set of ground motion time histories can be selected from real recorded or artificial time histories. The amplitude of these ground motions may be scaled but the phasing of Fourier components should be maintained. The adequacy of this set of ground motions, including duration estimates, is reviewed on a case-by-case basis. Option 1: Single Set of Time Histories. To be considered acceptable, the response spectra generated from the design time history to be used as input ground motion in the free-field should satisfy the enveloping criteria for either Approach 1 or Approach 2 below: i. Approach 1. For Approach 1, the spectrum from the design ground motion time history should envelop the free-field design response spectra for all damping values used in the seismic response analysis. When spectral values (e.g., spectral accelerations) are calculated from the design time history, the frequency intervals at which spectral values are determined are to be sufficiently small. Table 3.7.1-1 (below) provides