Publication and adoption of newer codes and standards has drastically changed the way many post-installed anchor products are tested, code evaluated, designed, specified, installed, and inspected. Following is a summary of the current industry design standard for common types of post-installed anchor products.
Establishing the design standard
There are many types of post-installed anchor products on the market, but some of the most commonly specified types are expansion anchors, screw anchors, adhesive anchors, and power-driven fasteners. The design standard for these anchors can vary based on not only the type of anchor, but also the type of base material the anchor is being installed into. Concrete and masonry are among the most common types of base materials for post-installed anchor products.
The 2012 International Building Code (IBC) includes information to establish the design standard for some of these anchors. When the design standard is not prescribed in IBC, the Referenced Standards may contain information to establish the design standard. Where neither the IBC nor its Referenced Standards specifically prescribe the standard for a specific anchor type, the product can be considered an alternative material per IBC Section 104.11. This section gives the building official the authority to approve the use of an alternative material, providing the material meets the intent of the code.
Section 104.11 also permits the building official to refer to research reports from approved sources in approving an alternate product. Two code compliance evaluation entities who issue most of the research reports for post-installed anchor products are International Code Council-Evaluation Services (ICC-ES) and International Association of Plumbing and Mechanical Officials-Uniform Evaluation Services (IAPMO UES). These agencies evaluate anchor products against various acceptance criteria (AC) that have been adopted by ICC-ES, often based on significant industry input.
Among various other things, the AC lists many tests that an anchor product must pass to be approved for certain applications. Once evaluated, the agency will issue an evaluation report that summarizes the conditions of use recognized as code compliant for the anchor product.
Post-installed anchoring into masonry
IBC Chapter 21 covers masonry, but there are no specific requirements within this chapter to define the specific design standard for post-installed anchor products. IBC Chapter 21 references TMS 402/ACI 530/ASCE 5 (ACI 530) for the design of masonry structures and ACI 530 contains design provisions related to anchoring into masonry. However, the provisions are specific to anchor bolts embedded in grout and do not specifically address post-installed anchor products.
So neither IBC nor ACI 530 establishes the design standard for post-installed anchors into masonry. Instead, the following documents represent the most current design standard for post-installed anchor products into masonry:
- ICC-ES AC01 Expansion Anchors in Masonry Elements
- ICC-ES AC58 Adhesive Anchors in Masonry Elements
- ICC-ES AC60 Anchors in Unreinforced Masonry Elements
- ICC-ES AC70 Fasteners Power-driven into Concrete, Steel and Masonry Elements
- ICC-ES AC106 Pre-drilled Fasteners (Screw Anchors) in Masonry
Post-installed anchoring into concrete
Two sections of IBC Chapter 19 specifically address anchorage to concrete: Section 1908, Anchorage to Concrete Allowable Stress Design, and Section 1909, Anchorage to Concrete Strength Design. Section 1908 does not address post-installed anchors (also referred to as anchors installed in hardened concrete), whereas Section 1909 does cover some post-installed anchor types.
Section 1909 requires that these anchors be designed in accordance with Appendix D of ACI 318, as amended by Section 1905, provided they are within the scope of Appendix D. The scope of Appendix D covers the design of post-installed anchor types such as adhesive anchors, expansion anchors, and undercut anchors. Appendix D requires that expansion and undercut anchors be tested to ACI 355.2, and adhesive anchors are to be tested to ACI 355.4.
Because IBC and its Reference Standards include specific provisions for these types of post-installed anchors, they are not necessarily considered alternative materials. However, ACI 318 Appendix D still requires the engineer to use design information taken from the post-installed anchor product evaluation report. In addition, Appendix D does not cover the design standard of common post-installed anchor types such as power-driven fasteners and screw anchors, nor does it cover common base materials such as lightweight concrete on metal deck.
As such, the following documents represent the most current design standard for post-installed anchor products into concrete:
- ICC-ES Acceptance Criteria 70 Fasteners Power-driven into Concrete, Steel and Masonry Elements
- ICC-ES Acceptance Criteria 193 Mechanical Anchors in Concrete Elements
- ICC-ES Acceptance Criteria 308 Post-installed Adhesive Anchors in Concrete Elements
In addition to including new design requirements for adhesive anchors, the 2011 edition of ACI 318 Appendix D (ACI 318-11) is the first building code to contain new requirements for specifying adhesive anchors. According to ACI 318-11, the contract documents shall specify all parameters associated with the adhesive bond stress used for design (such as minimum age of concrete prior to anchor installation, concrete temperature range, concrete moisture conditions during installation, hole drilling and preparation requirements, etc.). The term Manufacturers Printed Installation Instructions (MPII) is also introduced in ACI 318-11 and the contract documents shall require the installation of post-installed anchors in accordance with MPII.
IBC, its referenced standards, and industry AC have drastically changed the requirements for how engineers must now design and specify post-installed anchor products. Most of the new changes require that anchors now meet even more stringent test standards than those required in the past. In some cases, this has resulted in manufacturers phasing out some anchor products and introducing new ones.
It is important for engineers to know about these latest standards so they can design and specify anchor products appropriately. Engineers are encouraged to contact anchor manufacturers technical representatives for additional information that can help them ensure post-installed anchor products are properly designed and specified on future projects.
Kevin Davenport, P.E., is a field engineer with Simpson Strong-Tie based in Atlanta. He can be reached at firstname.lastname@example.org.