Document: NUREG-0800
Document ID: a8564bea-31bf-4592-ba45-e92b53d2d706
Document Type: srp
Title: SEISMIC SUBSYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340570.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.3
CFR Part: 
CFR Title: 

Content:
e of the increased analytical effort compared to the response spectrum techniques, usually only a major equipment system would warrant a time history approach. The time history approach does, however, provide more realistic results in some cases as compared to the res- ponse spectrum envelope method for multiply-supported systems. 10. Use of Equivalent Vertical Static Factors The acceptance criteria provided in SRP Section 3.7.2, subsec- tion II.10, are applicable. 11. Torsional Effects of Eccentric Masses For seismic Category I subsystems, when the torsional effect of an eccentric mass is judged to be significant, the eccentric mass and its eccentricity should be included in the mathematical model. The criteria for judging the significance will be reviewed on a case-by- case basis. 12. Category I Buried Piping, Conduits, and Tunnels. For Category I buried piping, conduits, tunnels, and auxiliary systems, the following items should be considered in the analysis: a. Two types of groundshaking-induced loadings must be considered for design. (i) Relative deformations imposed by seismic waves traveling through the surrounding soil or by differential deforma- tions-between the soil and anchor points. 3.7.3-5 Rev. 2 - August 1989 (ii) Lateral earth pressures and ground-water effects acting on structures. b. The effects of static resistance of the surrounding soil on piping deformations or displacements, differential movements of piping anchors, bent geometry and curvature changes, etc., should be adequately considered. Procedures using the principles of the theory of structures on elastic foundations are acceptable. c. When applicable, the effects due to local soil settlements, soil arching, etc., should also be considered in the analysis. d. Actual methods used for determining the design parameters associated with seismically induced transient relative deformations are reviewed and accepted on a case-by-case basis. Additional information, for guidance purposes only, can