Document: NUREG-0800
Document ID: 29f5ac9f-4962-4021-913a-6375076e03fd
Document Type: srp
Title: SEISMIC SYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340566.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
h appro- priate damping ratios for structure and soil subsystems. This method is based upon satisfaction of displacement compatibility and force equilibrium at the system interfaces and uses subsystem eigenvectors as internal generalized coordinates. This method results in a nonproportional damping matrix for the composite structure, and equations of motion have to be solved by direct integration or by uncoupling them by use of complex eigenvectors. Other techniques for estimating the equivalent modal damping of a soil- structure interaction model are reviewed on a case-by-case basis. 14. Determination of Category I Structure Overturning Moments To be acceptable, the determination of the design overturning moment should incorporate the following items: a. Three components-of input motion. b. Conservative consideration of vertical and lateral seismic forces. III. REVIEW PROCEDURES For each area of review, the following procedure is implemented. The reviewer will select and emphasize material from the procedures given below, as may be appropriate for a particular case. The scope and depth of review procedures must be such that the acceptance criteria described above are met. 1. Seismic Analysis Methods. For all Category I structures, systems, and components, the applicable methods of seismic analysis (response spectra, time history, equivalent static load) are reviewed to confirm that the techniques employed are in 3.7.2-17 Rev. 2 - August 1989 accordance with the acceptance criteria as given in subsection 11.1 of this SRP section. If empirical methods or tests are used in lieu of analysis for any Category I structure, these are evaluated to determine whether or not the assumptions are conservative, and whether the test procedure adequately models the seismic response. 2. Natural Frequencies and Response Loads For the operating license review, the summary of natural frequencies and response loads is reviewed for compliance with the acceptance criteria in subsection