A concrete anchor system with a mechanical connection—not a friction-fit
The DUC Undercut Anchor consists of an ASTM A36 or A193 Grade B7 threaded stud, a thick-walled expansion sleeve, an expander coupling, and a nut and washer. All DUC Undercut Anchors are also available in 316 stainless steel versions.
How it Works
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 USP DUC Undercutting Bit.
The DUC Undercutting Bit 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 expansion sleeve is driven over the expander coupling.
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), the DUC 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 ensures ductile behavior of the anchor even at relatively shallow embedments.
The DUC Undercut Anchors have been tested in accordance with ACI 355.2 to be qualified for use with the design methods of ACI 318 appendix.
DUC Undercut Anchor Advantages
Compared with heavy capacity 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.
- Large bearing area provides exceptional performance even in lower strength concrete.
- Load transfers mainly through bearing, not expansion forces and is 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. Full ultimate steel strength of the threaded stud is developed at listed embedment and spacing. Stainless steel is also available.
- 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.
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