Document: NUREG-0800
Document ID: 1f106a50-722f-45fa-952a-2e7ab7d836c1
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, COMPONENTS, AND EQUIPMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052360453.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
CFR Part: 
CFR Title: 

Content:
rthquake should be obtained from the synthetic time history (with a minimum duration of 10 seconds) used for the system analysis, or a minimum of 10 maximum stress cycles per earthquake may be assumed (extract from SRP Section 3.7.3, subsection I1.2). c. Basis for Selection of Frequencies To avoid resonance, the fundamental frequencies of. components and equipment should preferably be selected to be less than 1/2 or more than twice the dominant frequencies of the support structure. Use of equipment frequencies within this range is acceptable if the equipment is adequately designed for the applicable loads. 3.'9. 2- 7 Rev. 2 - July 1981 d. Three Components of Earthquake Motion Depending upon what basic methods are used in the seismic analysis, i.e., response spectra or time history method, the following two approaches are considered acceptable for the combination of three-dimensional earthquake effects. (Ref. 11, 12, and 13) (1) Response Spectra Method When the response spectra method is adopted for seismic analysis, the maximum structural responses due to each of the three components of earthquake motion should be com- bined by taking the square root of the sum of the squares of the maximum codirectional responses caused by each of the three components of earthquake motion at a particular point of the structure or of the mathematical model. (2) Time History Analysis Method When the time history analysis method is employed for seismic analysis, two types of analysis are generally performed depending on the complexity of the problem. (a) to obtain maximum responses due to each of the three com- ponents of the earthquake motion: in this case the method for combining the three-dimensional effects is identical to that described in (a) except that the maximum responses are calculated using the time history method instead of the spectrum method. (b) To obtain time history responses from each of the three components of the earthquake motion and combine them at each time