StructuralEIT, talk to the local field rep. They are currnetly working with ACI to determine how the loads should be distributed to the anchors until they are given guidance they have chosen this route according to there rep. The most they have touched the subject is in the commentary in fig RD.6.2.1(b) of ACI 318-08 unless the anchors are rigidly attached case one is used. This is not the fault of either Hilti or Simpson or them just wanting to be conservative, they have not been given direction from ACI on how they should handle shear load distribuation. This is way beyond being conservative just because the behavior is not clearly understood. I would love to see a shear breakout test on a 14'x8" THK. Just to give you example had to check a beam connection and embed plate with 6 HSA 9" spacing, for about 13k at the top of a 14' wall loaded towards the foundation, both Simpson and Hilti said the connection fails under D+L.
He is not talking about pryout, which rarely governs shear limit states, the one which normally governs is shear breakout, which is even more conservative than tension breakout, if anyone can believe that.
With those unknowns, why not accept a conservative but widely accepted value for shear resistance frm the actual vender you are using? RE: Hilti Profis sandman21 (Structural) 22 Sep 09 23:16 Now for prying, the real problem is trying to (accurately enough!) predict the LOCATION of bending line of the anchor plate under the actual ultimate moment load the direction of the ultimate bending moment load the actual amount of the bending moment the resistance of the anchor plate to bending about that (unknown and only guessed at) bending (line) location and the strenght of the concrete, concrete-to-bolt, and bolt+nut strength that are resisting the (unknown but guessed at) bending moment at the (unknown but guessed at) bending line location. That's not really a bad thing - considering that their equations are going to holding up things above people's heads and property.īut think about this particular shear prediction: Shear is rarely the limiting issue in concrete anchors Prying is the limiting value (pulling the anchor out of the surface of the concrete, rather than cutting the anchor bolt in half due to shear loads.) So, since shear isn't a limit, why not check the connection array for shear conservatively? OK, so Hilti is "conservative" when trying to predict (not calculate) shear in their anchor bolts.
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