Document: NUREG-0800
Document ID: 786da65a-4915-4af3-afb3-678b7df5bea7
Document Type: srp
Title: OTHER SEISMIC CATEGORY I STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070327.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.4
CFR Part: 
CFR Title: 

Content:
996 When pool walls are utilized to provide lateral restraint at higher elevations, a determination of the flexibility of the pool walls and the capability of the walls to sustain such loads should be provided. If the pool walls are flexible (having a fundamental frequency less than 33 Hertz), the floor response spectra corresponding to the lateral restraint point at the higher elevation are likely to be greater than those at the base of the pool. In such a case using the response spectrum approach, two separate analyses should be performed as indicated below: (a) A spectrum analysis of the rack system using response spectra corresponding to the highest support elevation provided that there is not significant peak frequency shift between the response spectra at the lower and higher elevations; and (b) A static analysis of the rack system by subjecting it to the maximum relative support displacement. The resulting stresses from the two analyses above should be combined by the absolute sum method. In order to determine the flexibility of the pool wall it is acceptable for the applicant to use equivalent mass and stiffness properties obtained from calculations similar to those described in Ref. 4.1. Should the fundamental frequency of the pool wall model be higher than or equal to 33 Hertz, it may be assumed that the response of the pool wall and the corresponding lateral support to the new rack system are identical to those of the base slab, for which appropriate floor response spectra or ground response spectra may already exist. (6) Structural Acceptance Criteria The structural acceptance criteria are those given in the Table 1. When buckling loads are considered in the design, the structural acceptance criteria shall be limited by the requirements of Appendix XVII to Reference 3.1. For impact loading, the ductility ratios utilized to absorb kinetic energy in the tensile, flexural, compressive, and shearing modes should be quantified. When considering the effects of