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:
ing responses tends to yield over-conservative results. To obviate this problem, a general approach applicable to all modes is considered appropriate. The following equation is merely a math- ematical representation of this approach. The most probable system response, R, is given by R =(I R + 2 2 | RmR 1)1/2 (2) k = I Where the second summation is to be done on all £ and m modes whose frequencies are closely spaced to each other. Other approaches which give an equivalent degree of conserva- tism to the above methods, and which are adequately justified are also acceptable. Regulatory Guide 1.92 (Reference 10) "Combining Modal Responses and Spatial Components in Seismic Response Analysis" presents detailed guidance on this topic. f. Analytical Procedures for Piping Systems The seismic analysis of Category I piping may use either a dynamic analysis or an equivalent static load method. The acceptance criteria for the dynamic analysis or equivalent static load methods are as given in subsection II.2.a of this SRP section. g. Multiply-Supported Equipment and Components With Distinct Inputs Equipment and components in some cases are supported at several points by either a single structure or two separate structures. The motions of the primary structure or structures at each of the support points may be quite different. A conservative and acceptable approach for equipment items sup- ported at two or more locations is to use an upper bound envelope of all the individual response spectra for these locations to calculate maximum inertial responses of multiply-supported items. In addition, the relative displacements at the support points should be considered. Conventional static analysis procedures are acceptable for this purpose. The maximum relative support 3.9.2-9 Rev. 2 - July 1981 displacements can be obtained from the structural response cal- culations or, as a conservative approximation, by using the floor response spectra. For the latter option, the maximum dis-