Document: NUREG-0800
Document ID: 585516eb-af20-45dc-a470-9638ec9381f3
Document Type: srp
Title: Each calculated spectrum of the artificial time history is considered to envelop
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640306.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.0
CFR Part: 
CFR Title: 

Content:
centage of critical damping values used in the analyses of Category I SSCs are considered to be acceptable if they are in accordance with RG 1.61. Damping values different from those listed in RG 1.61 (e.g., higher damping values) may be used in a dynamic seismic analysis if test data are provided to support them. These damping values will be reviewed and accepted by the staff on a case-by-case basis. In addition, a demonstration of the correlation between stress levels and damping values will be required and reviewed for compliance with the applicable regulatory position in RG 1.61. If other methods for correlation of damping values with stress level are used, they will need to be reviewed and accepted on a case-by-case basis. The material soil damping for foundation soils must be based upon validated values or other pertinent laboratory data, considering variation in soil properties and strains within the soil, and must include an evaluation of dissipation from pore pressure effects as well as material damping for saturated site conditions. The maximum soil damping value acceptable to the staff is 15 percent. 3. Supporting Media for Seismic Category I Structures. To be acceptable, the description of supporting media for each Category I structure must include foundation embedment depth, depth of soil over bedrock, soil layering characteristics, design groundwater elevation, dimensions of the structural foundation, total structural height, and soil properties such as shear wave velocity, shear modulus, Poisson's ratios, and density as a function of depth. If the minimum shear wave velocity of the supporting foundation material is less than 1,000 fps, additional studies need to be performed which consider the average shear wave velocity, and its degree of variability addressing potential impact on soil-structure interaction, potential settlements and design of foundation elements. 4. Review Considerations for DC and COL Applications A. COL Application Referencing an