Document: NUREG-0800
Document ID: 6b7eddf4-f7ce-4821-9f11-e37070221e57
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, STRUCTURES, AND
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1613/ML16133A418.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
CFR Part: 
CFR Title: 

Content:
rom the combined time solution. When this method is used, the earthquake motions specified in the three different directions should be statistically independent. E. Combination of Modal Responses. SRP Section 3.7.2 and RG 1.92 present criteria and guidance for modal response combination methods acceptable to the staff. F. Analytical Procedures for Piping Systems. The seismic analysis of Seismic 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 described in subsection II.2.A of this SRP section. 3.9.2-18 Revision 4 – March 2017 G. Multiple-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 significantly different. A conservative and acceptable approach for equipment items supported at two or more locations is to use an upper-bound envelope of the individual response spectra for these locations to calculate maximum inertial responses of multiple-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 displacements can be obtained from the structural response calculations or, as a conservative approximation, from the floor response spectra. For the latter option, the maximum displacement of each support (Sd) is predicted by: 2 /ω g S S a d = where Sa is the spectral acceleration in the unit of "g” at the high frequency end of the spectrum curve (which, in turn, is equal to the maximum floor acceleration), g is the gravity constant, and ω is the fundamental frequency of the primary support structure in radians per second. The support displacements can then be imposed on the