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DUC Undercut Anchors

How it works

The DUC Undercut Anchor consists of a ASTM A36 or A193 Grade B7 threaded stud, a thick walled expansion sleeve, an expander coupling and a nut and washer.

The DUC Undercut Anchor is installed into a pre-drilled hole which has been enlarged at the bottom in the shape of a reversed cone. The reverse cone is created using the Covert Operations DUC Undercutting Bit which fits into SDS or SDS-Max rotary hammer drills and guarantees the correct angle of the reverse cone. The anchor is expanded into the reverse cone when the nut is turned and the expander coupling is pulled up into the expansion sleeve.

The result is an anchor which transfers load mainly through bearing, and unlike a typical expansion anchor (sleeve, heavy duty sleeve, wedge and drop-ins), is not dependent upon friction between the expansion sleeve and the concrete. Due to the use of a thick walled expansion sleeve, the load is distributed to a large area which virtually insures ductile behavior of the anchor even at relatively shallow embedments.

The DUC Undercut Anchor has been tested to the requirements of ACI 355.2 (-07, -04) for use in seismic, cracked and uncracked concrete applications, and meets the ACI 318-14 Chapter 17 (2018 IBC).

DUC Undercut Anchor Advantages vs. Heavy Duty Sleeve and Expansion Anchors and other undercut systems. 

  • DUC Undercut Design provides consistent expansion and is easy to set. Stress risers have been eliminated to prevent tearing.
  • Largest bearing area provides exceptional performance even in low strength concrete.
  • Load transfers mainly through bearing, not expansion forces. They are not dependent upon friction which can be lost when cracks occur.
  • Thick walled sleeves transfer load over a larger area which insures predictable ductile performance.
  • ASTM A36 or A193 grade B7 rods are used. These are true ductile materials. Full ultimate steel strength is developed at listed embedment and spacing.
  • Installation is simple. It is similar to installing a typical expansion anchor; no coring drills are necessary. Creation of proper undercut is correctly done and easily verified using DUC undercut bits. Creation of undercut takes only seconds.
  • May be installed with or without special inspection. Installation costs are reduced without these inspections. Allowable loads are higher with special inspections.