Document: NUREG-0800
Document ID: 7c104096-d040-463a-a94b-a0af08ab3478
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, STRUCTURES, AND
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0702/ML070230008.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
CFR Part: 
CFR Title: 

Content:
mic modeling to determine the response of all Category I and applicable non-Category I systems and plant equipment. The number is adequate when additional degrees of freedom do not result in more than a 10-percent increase in responses. Alternately, the number of degrees of freedom may be taken as equal to twice the number of modes with frequencies less than 33 Hz. (3) Investigation of a sufficient number of modes to ensure participation of all significant modes. The criterion for sufficiency is that the inclusion of additional modes does not result in more than a 10-percent increase in responses. (4) Consideration of maximum relative displacements among supports of Category I systems and components. (5) Inclusion of such significant effects as piping interactions, externally-applied structural restraints, hydrodynamic (both mass and stiffness effects) loads, and nonlinear responses. (ii) Equivalent Static Load Method. An equivalent static load method is acceptable if: (1) There is justification that the system can be realistically represented by a simple model and the method produces conservative results in responses. Typical examples or published results for similar systems may be submitted in support of the use of the simplified method. (2) The design and simplified analysis account for the relative motion between all points of support. (3) To obtain an equivalent static load of equipment or components which can be represented by a simple model, a factor of 1.5 is applied to the peak acceleration of the applicable floor response spectrum. A factor of less than 1.5 may be used with adequate justification. 3.9.2-12 Revision 3 - March 2007 In addition, for equipment which can be modeled adequately as a one-degree-of-freedom system, the use of a static load equivalent to the peak of the floor response spectra is acceptable. For piping supported at only two points, the use of a static load equivalent to the peak of the floor response spectra is also acceptable. B.