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:
The staff does not endorse the application of “one-third greater than that required by analysis” provision to the minimum reinforcement provided in Section 7.12.4 of ACI 349-13. 2.7 Section 7.12.4 of ACI 349-13 does not address minimum reinforcement for the foundation base mat. The ratio of nonprestressed reinforcement area to gross concrete area, on a tension face of a foundation base mat, where a calculated reinforcement DG-1283, Page 11 requirement exists, should not be less than 0.0018 in the direction of the span under consideration. 2.8 To determine the shear strength of slabs and walls for concentrated loads or reactions perpendicular to the plane of the slabs and walls, the effective width of the critical section for the beam action condition is the zone of influence induced by the concentrated loads instead of the entire width of the slab as specified in Section 11.11.1.1 of ACI 318-08, which is incorporated by reference in Section 11.9 of ACI 349-13. The effective zone of influence may be determined, for example, by analysis. 3. Regulatory Position 3 The staff endorses the load combinations in Section 9.2 of ACI 349-13, as modified in Regulatory Position 3.1 and outlined in Table 2 (modifications of load factors indicated in bold italic font). 3.1 Table 2. Loads, Load Factors and Load Combinations Required Strength (U) Load Combinations ACI Equations U = 1.4(D + F) + Ro + To (9-1) (NL) U = 1.2(D + F ) + 1.6(L + H + Ro + To) + 1.4Ccr + 0.5(Lr or S or R) (9-2) (NL) U = 1.2(D + F) + 0.8L + H+ Ro + To + 1.4Ccr + 1.6(Lr or S or R) (9-3) (NL) U = 1.2(D + F ) + 1.6(L + H + Ro + Eo) + 1.4Ccr (9-4) (SEL) U = 1.2(D + F) + 1.6(L + H + Ro + W) (9-5) (SEL) U = D + F + 1.0L + Ccr + H + To + Ro + Ess (9-6) (EEL) U = D + F + 1.0L + H + To + Ro + Wt (9-7) (EEL) U = D + F + 1.0L + Ccr + H + Ta + Ra + 1.4Pa (9-8) (AL) U = D + F + 1.0L + H + Ta + Ra + Pa + Yr + Yj + Ym + Ess (9-9) (AL) Legend NL = Normal Loading condition SEL = Severe Environmental Loading condition EEL =