US 5,685,678 AGranted

Fail-safe anchor bolt assembly for cracked masonry

OwnerAnthony C. Giannuzzi, Louis N. Giannuzziinventors

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Abstract

A fail-safe anchor bolt assembly installable in a pre-drilled hole in masonry to fasten a fixture or other object thereto, the assembly remaining securely anchored even should the hole later be enlarged as a result of a crack developed in the masonry. The assembly includes a bolt having a head engageable by a torque tool to turn the bolt and a shank extending from the head loosely encircled by an expansible shell whose normal outer diameter is close to that of the drilled hole. Threadably received on the end of the shank adjacent the shell is a wedge nut having a generally conical frustrum shape defining a leading end followed by a leading portion which merges with a compressible trailing portion terminating in a trailing end, the leading portion having a maximum diameter close to the diameter of the drilled hole and the compressible trailing portion having a normal maximum diameter greater than the diameter of the drilled hole. When the assembly is installed in a drilled hole, the leading portion of the nut enters into and acts to expand the shell against the wall of the hole to provide an anchoring force. But should a crack later develop in the masonry resulting in an enlargement of the drilled hole, the trailing portion then enters the shell to further expand it to maintain the anchoring force.

A fail-safe anchor bolt assembly installable in a hole drilled in masonry subject to cracking to fasten an object thereto provided with a mounting hole, said assembly comprising a bolt turnable by a torque tool, said bolt having a head, a threaded stud projecting above the head receivable in the mounting hole of the object, a shank extending below the head, an expansible shell surrounding the shank, and an internally-threaded wedge nut threadably received on the shank and adapted when the bolt is turned to enter into and expand the shell outwardly against the wall of the hole, said wedge nut having a generally conical frustrum shape defining a leading end followed by a leading portion which merges with a compressible trailing portion terminating in a trailing end, said shape being characterized by a substantially uninterrupted transition in diameter which increases progressively from the leading end to the trailing end, said leading portion having a maximum diameter close to the diameter of the drilled hole, said compressible trailing portion having a normal maximum diameter greater than the diameter of the drilled hole whereby:

A. when the assembly is driven into the drilled hole, the trailing portion of the wedge nut is then compressed to permit entry therein and to prevent its rotation so that as the bolt is turned by the tool, the non-rotating wedge nut advances axially on the shank to cause the leading portion to enter into and expand the shell outwardly against the wall of the hole to produce an anchoring force to fasten the object to the masonry;
and
B. should the masonry thereafter develop a crack resulting in enlargement of the drilled hole, the fastened object loading the assembly will then move the trailing portion of the wedge into the shell to further expand it outwardly against the wall of the enlarged hole, this movement of the wedge nut causing a non-interrupted and continuous expansion of the shell as the wedge nut advances into the shell, thereby avoiding an uncontrolled slip of the wedge nut and maintaining the anchoring force fastening the object to the masonry.

Abstract

Claims11