Document: NUREG-0800
Document ID: c165ebfe-8431-4d56-8bc9-97c2227d45bb
Document Type: srp
Title: SEISMIC SYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640311.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
gle time history analysis, the statistical independence among the three components is also reviewed. 7. Combination of Modal Responses. When a modal time history analysis method or a response spectrum analysis method is used to calculate the seismic response of SSCs, the contribution to the total response due to the effects of high frequency modes (i.e., modes with natural frequencies greater than the frequency at which the spectral acceleration converges to approximately the zero period frequency, ZPA) is reviewed, to ensure that the total response closely simulates the behavior of the SSC during a seismic event. For the case of the Regulatory Guide (RG) 1.60 response spectrum, ZPA is about 33 Hz. When a response spectrum method is used, the procedure for combining modal responses, including modes with closely spaced frequencies, is reviewed. 8. Interaction of Non-Category I Structures with Category I SSCs. The design criteria to account for the seismic motion of non-Category I structures (or portions thereof) in the seismic design of Category I structures (or portions thereof) are reviewed. The seismic design of structures whose continued function is not required but whose failure could adversely impact the safety function of a Category I SSC, or result in incapacitating injury to control room occupants, is reviewed. Any special design features employed to protect Category I SSCs from the structural failure of non-Category I structures, due to seismic effects, are reviewed. 9. Effects of Parameter Variations on Floor Responses. The procedures that are used to consider the effects of the expected variations of structural properties, critical damping values, soil properties, and SSI on the floor response spectra and response time histories are reviewed. 3.7.2-4 Revision 3 - March 2007 10. Use of Equivalent Vertical Static Factors. Where applicable, justification for the use of equivalent vertical static load factors in calculating the vertical response loads for