Tested some "new" Star Dryvins
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Banquo

climber
Amerricka
Topic Author's Reply - Apr 6, 2013 - 09:32pm PT
Tested some 3/8 wedge anchor in 1-1/4" deep holes.

Tension failed at 5100 pounds. It popped a flat plate of granite off and I hypothesize that I didn't get the classic 45 degree cone because the outward force of the wedge rotated the principal stresses in the rock near the bolt. I'll draw Mohr's circle and explain this if anybody really, really wants me to. If you do use shorty bolts, be sure the rock near the surface is good.


I did the same with loading in shear. the stud sheared off at 5070 pounds which is probably stronger than most hangers.


The wedge anchor is certainly good enough in a 1.25" deep hole. The rock may not be which may be hard to judge in the field. On the other hand, many of us have spent years climbing on 1/4x1-1/4 buttonhead split shank anchors which have much less capacity.
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