Document: NUREG-0800
Document ID: e7548e72-8c59-4c82-98dd-ff425e1de29a
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1235/ML12352A305.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
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CFR Title: 

Content:
energy losses that depend on numerous factors, such as material characteristics, stress levels, and geometric configuration. This dissipation of energy, or damping effect, occurs because a part of the excitation input is transformed into heat, sound waves, and other energy forms. The response of a system to dynamic loads is a function of the amount and type of damping existing in the system. Knowledge of appropriate values to represent this characteristic is essential for obtaining realistic results in any dynamic analysis. In practical seismic analysis, which usually employs linear methods of analysis, damping is also used to account for many nonlinear effects such as changes in boundary conditions, joint slippage, concrete cracking, gaps, and other effects that tend to alter response amplitude. In real structures, it is often impossible to separate "true" material damping from system damping, which is the measure of the energy dissipation, from the nonlinear effects. Overall structural damping used in design is normally determined by observing experimentally the total response of the structure. Damping values assigned to members of seismic Category I SSCs, including material damping and system damping, are reviewed. When applicable, the basis for any damping values that differ from those given in RG 1.61 is reviewed. 3. Supporting Media for Seismic Category I Structures. The description of the supporting 3.7.1-5 Draft Revision 4 - December 2012 media for each seismic Category I structure is reviewed, including foundation embedment depth, depth of soil over bedrock, soil layering characteristics, highest groundwater elevation, dimensions of the structural foundation, total structural height, topographical conditions of the sites, and soil properties to permit evaluation of the applicability of finite-element or lumped-spring approaches for soil-structure interaction analysis. 4. Review Considerations for DC and COL Applications. For a DC application, the postulated