Document: NUREG-0800
Document ID: 4833ef26-8adf-4cbe-ae0e-b35c9972795a
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A223.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
Revision 4 – September 2013 which is a function of the level of stress due to the most critical load combination. The effects of concrete cracking on membrane, bending, and shear stiffness should be considered as appropriate in the mathematical model. Because the effect of cracking on the stiffness of concrete members is complex and depends on a number of factors, the approach used should be shown to be conservative. One approach for considering the cracked concrete properties is to reduce the stiffness properties of the uncracked members by a reduction factor. Acceptable stiffness reduction factors for cracked concrete members are given in American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI) 43-05 (e.g., 0.5 for cracked walls for flexure and shear). If structural responses (e.g., member forces, displacements, soil bearing pressures) are determined from a separate detailed finite element analysis (what is referred to as a two-step approach), the effects of concrete cracking should be considered both in the SSI analysis and the detailed structural analysis. Further guidance on consideration of concrete cracking in the analysis and design for seismic Category I structures is provided in the acceptance criteria for design and analysis procedures presented in SRP Sections 3.8.1 and 3.8.3 through 3.8.5. For the generation of ISRS, the guidance given below should be followed. For a generic design, where the design-basis ISRS represent the envelope of the in-structure responses obtained from multiple analyses conducted to consider the range of expected site soil conditions associated with the certified seismic design response spectra (CSDRS), the cracked concrete properties and the associated SSE damping values in Table 1 of RG 1.61, can be used. If a CSDRS is associated with a single site condition, such as the hard-rock high-frequency (HRHF) spectra for a specific site, then the use of uncracked concrete properties with OBE damping values in