Document: NRC Regulatory Guide
Document ID: fcaa3426-5268-4adb-a83c-69e7f50d6d6b
Document Type: regulatory_guide
Title: Anchoring Components and Structural Supports in Concrete (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1725/ML17258A579.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.199
CFR Part: 
CFR Title: 

Content:
This inspection element will detect gross defects in the concrete that could affect the holding power of expansion anchor bolts. Hairline shrinkage cracks in the vicinity of an expansion bolt are not a matter of concern as long as the design strength is based on cracked concrete. If cracks in the vicinity exceed about 0.01 inch (0.3 millimeter), the design strength should be appropriately reduced. 2.6 Is there a significant gap between the equipment base and the concrete surface? This inspection element will identify situations in which the equipment base is raised. This detail causes concern because shear forces result in flexural stresses in the anchor bolt. A gap of less than about 0.25 inch is not significant and should be ignored, except, for equipment that contains essential relays (a relay whose function is essential to plant safety in an earthquake), there should be no gap between the base of the equipment and the surface of the concrete at the bolt or anchor location. Anchorages with gaps larger than about 0.25 inch should be evaluated in more detail. For maximum assurance, all six of these steps should be performed for all bolts. However, adequate assurance can be achieved by a less extensive inspection program. Inspection steps 2.2 through 2.6, which are simple and mainly visual, should be applied to each bolt together with a sampling approach for the tightness check in step 2.1. Appendix A to this guide provides a sampling program for expansion anchor bolts. 3. Quality Assurance The methods for design and construction QA found in RG 1.28, “Quality Assurance Program Criteria,” should be used. 4. Anchorage to Masonry Anchorage to masonry structures and components is outside the scope of ACI 349-13. Anchors discussed in this guide should not be used to attach seismic Category I components or systems to concrete block (masonry) walls that are seismically qualified, except for extremely low-load applications. When it is impossible to avoid their