Ductile Limit States Using Post-Installed Anchors

I am reaching out to ask whether Hilti has conducted any analysis, research, or published guidance on ways post-installed anchors can be used to achieve ductile limit states at column bases.

With the recent update to AISC Design Guide 1 (DG 1), Base Plate and Anchor Rod Design, and with states adopting IBC 2024 (referencing AISC 341‑22), there is focus on ductile behavior in base connections. Under AISC 341‑16, foundations resisting overturning were required either to develop the full design strength of the column section or to be designed for seismic forces including overstrength, while still achieving a ductile limit state.

As you know, interpretation of the code and design guides can vary. While AISC 341 identifies several ductile limit states for column bases paired with stringent ductility requirements, DG 1 strongly advocates for treating the anchor rods as the ductile element. DG 1 also notes that ductile elements retain strength even under large deformations, which means brittle elements may continue to be stressed and potentially fail; it then outlines preferred failure modes. In the extreme, DG 1 even presents a reduced‑diameter anchor rod concept specifically intended to enforce ductile behavior.

Another possible approach is to follow ACI 318 provisions, which are less prescriptive about verifying ductility but are fully codified, unlike DG 1. A common thread among all three documents is the concept of anchor elongation. One practical way to achieve the required stretch length is the use of anchor “chairs” or wrapping the anchor to prevent bonding over a length equal to approximately eight times the anchor diameter—thus forcing yielding to occur in the anchor rod itself.

My questions for Hilti are:

1. Does Hilti have documentation, testing, or recommendations regarding preventing bonding of post-installed anchors over a prescribed embedment length (e.g., the top of base plate to ~8 anchor diameters below)?
2. Has Hilti studied or developed prescriptive methods, such as sleeves, wraps, or other detailing, to facilitate ductile anchor behavior in column-base applications?
3. Are there any Hilti research efforts underway or planned that focus on achieving ductile limit states with post-installed anchors in seismic base connections?

It appears that industry research is increasingly moving toward solutions that enable ductile behavior in anchorage, and I would like to better understand what options Hilti currently offers or anticipates offering in this area.