Monday, October 29, 2007

RE: Anchor Shear Shear Capacity in Reinforced Concrete

I've had somebody argue with me that the shear friction formula requires you
to have some reinforcement parallel to the anchor or perpendicular to the
shear crack for your popout cone free body diagram to work right with the
shear friction formula.

I've heard that people use reinforcement perpendicular to the anchor to
develop shear friction but I have not seen a published example of this. If
there is a published example in some industry literature I would like to see

-----Original Message-----
From: M. David Finley, P.E., P.A. []
Sent: Monday, October 29, 2007 12:40 PM
To: Seaint@Seaint.Org
Subject: Anchor Shear Shear Capacity in Reinforced Concrete

ACI 318-05 Appendix D, Section 4.2.1 has only a brief discussion of using
supplementary reinforcing in lieu of the Appendix D methodology. Can
somebody suggest some references (preferably including examples) of using
supplementary reinforcing for increased shear capacity?

My application is doweling into the edge (the 12" dimension) of an existing
reinforced 12" thick slab. With the dowels centered in the slab, there is
not enough effective embedment depth to develop enough shear resistance
perpendicular to the face of the slab. I'm trying to find a rational
procedure for determining the shear capacity of the dowel considering the
effects of the existing slab reinforcing.

Would the shear friction provisions of 11.7.4 be applicable? Or does the
shear cone make that approach invalid?


David Finley
M. David Finley, P.E., P.A.
2086 SW Main Boulevard - Suite 111
Lake City, FL 32025

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