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:
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 supported item in the worst case combination. The responses due to the inertia effect and relative displacements should be combined by the absolute sum method. In the case of multiple supports located in a single structure, an alternate acceptable method using the floor response spectra determines dynamic responses due to the worst case single floor response spectrum selected from a set of floor response spectra at various floors and applied identically to all the floors provided there is no significant shift in frequencies of the spectra peaks. In addition, the support displacements should be imposed on the supported item in the most unfavorable combination by static analysis procedures. Further criteria and methods for the evaluation of multiple support arrangement analysis issues are described in SRP Sections 3.7.2 and 3.7.3. These methods can result in overestimation of seismic responses. Acceptable alternate response spectrum analysis methods that provide more realistic estimation of seismic responses are discussed in subsection II.9 of SRP Section 3.7.3. In lieu of the response spectrum approach, time histories of support motions may be used as excitations to the systems. Because 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 response spectrum envelope method for multiple-supported systems. 3.9.2-19 Revision 4 – March 2017 H. Use of Constant Vertical Static Factors. The use of constant vertical load factors as vertical response loads for the seismic design of all seismic Category I systems, components, equipment, and their supports in lieu of a