Document: NRC Regulatory Guide
Document ID: 0ae1e098-eccd-43e7-b12e-43b05aa1fe48
Document Type: regulatory_guide
Title: Safety-Related Concrete Structures for Nuclear Power Plants (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1617/ML16172A240.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.142
CFR Part: 
CFR Title: 

Content:
completed structures, and by considering in the design the construction loads induced in partially completed structures and temporary structures and supports, as well as applicable load combinations. Structural Engineering Institute/ American Society of Civil Engineers (ASCE) Standard 37, “Design Loads on Structures during Construction” (ASCE 37), gives additional guidance on construction loads. The NRC staff does not endorse ASCE 37; however, the staff recognizes that this standard can provide additional information. To the extent licensees or applicants rely on ASCE 37, they should provide sufficient basis and information to the staff to verify consistency applicable to NRC requirements. In addition, in cases where the criteria in ASCE 37 conflict with this RG, licensees and applicants should follow the positions in this RG. 3.6 The commentary of ACI 349-13 does not provide sufficient justification for the 10 percent reduction in the load factor for the effects of the seismic load Ess in Section 9.2.10 of ACI 349-13. Therefore, in load combinations (9-6) and (9-9), the NRC does not endorse reducing the load effects of the seismic load Ess by 10 percent provided in Section 9.2.10 of ACI 349-13. 3.7 This regulatory position refers to strength reduction factor (φ) for shear critical members such as low-rise shear walls, portions of walls between openings or diaphragms. The regulatory position reflects the lower ductility and ability to redistribute loads of these shear critical members as compared to flexure-critical members. In Section 9.3.4 and R9.3.4 of ACI 318, φ = 0.60 is used for shear critical members. Commentary section R9.3.1 of ACI 349-13 recommends using φ = 0.75 for such members but the justification provided for using higher φ value is not defensible. The NRC Staff position is to use φ= 0.60, which provides margin to account for uncertainties and variability in the shear capacity and the consequences of brittle failure. This discussion also