Document: NUREG-0800
Document ID: 9f8ed031-87a1-4c78-bba4-d0e59f9ba1e5
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1235/ML12353A354.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
gh- frequency (HRHF) spectra for a specific site, then the use of uncracked concrete properties with OBE damping values in Table 2 of RG 1.61 are acceptable to develop ISRS. An acceptable approach for existing structures or site-specific designs, where it is not desirable to utilize the approach described above, a seismic analysis can be performed based on the best estimates of the stiffness properties of the structural members. A mathematical model of the structure should be developed to be representative of the structure and analyzed for the uncracked stiffness properties. The analysis may be performed by assuming, for shear walls as an example, in-plane bending and shear stiffness values corresponding to the uncracked properties, and a damping value of 4 percent. After performing the seismic analysis, the calculated state of stress in the concrete members should be compared to the stresses that would cause cracking, for all load combinations that include seismic effect. If extensive cracking is determined based on this stress comparison, then the stiffness of those