Document: NUREG-0800
Document ID: 2d2b9404-d124-483c-971a-a8f564048299
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640306.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
defined in SRP Section 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 5% to 75%. 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, the ratios V/A and AD/V2 (A, V, D are peak ground acceleration, ground velocity, and ground displacement, respectively) should be consistent with 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 shall be selected from real recorded ground motions appropriate for the characteristic low and high frequency events. The 3.7.1-10 Revision 3 - March 2007 amplitude of these ground motions may be scaled but the phasing of Fourier components must 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 artificial time history to be used as input ground motion in the free-field should satisfy the enveloping requirements for either Approach 1 or Approach 2 below: i. Approach 1. For Approach 1, the spectrum from the artificial ground motion time history must 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 artificial time history, the frequency intervals at which spectral values are determined are to be