I would like to embed 3/4" diameter epoxy threaded rods more than the 15" embedment limit to get down through a topping slab. Is there any issue with this as long as the calculations only rely on 15" embedment? Why is there the limit?
Hi Maureen,
ACI 318-19 Section 17.3.3 limits the embedment depths of adhesive anchors to a maximum of 20 times the diameter of the anchor. To comply with the code requirements, Hilti limits the maximum embedment depths to this requirement.
Regards,
Ashley
Hi Maureen,
Although increasing the embedment depth, under anchor design theory (ACI 318-14 Chapter 17) should yield higher load capacities the relationship and predictability of the potential failure modes will also change. Typically engineers will refer to the study, Eligehausen et al. 2006a, referenced in ACI-318-19 R17.3.3 for further information.
Not all adhesive anchor systems may be suitable for deeper embedment, regardless of the design theory used to calculate anchor capacity, and the manufacturer should be consulted. Hilti has qualified HIT-RE 500 V3 (ESR-3814) and HIT-HY 200 (ESR-3187) for deep embedment depths using rebar development theory as referenced in the ESRs.
Engineering judgment is typically utilized to determine capacity based on the limited data available in conjunction with field testing the anchor to a proof load.
Regards,
Ashley