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Re: shear friction from horizontal top reinforcement, to resist holdown anchor pop out in A footing?

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halo !
i've seen this used somewhere for a beam in a wall scenario.
can't recall the source.

On 10/3/06, Haan, Scott M POA <Scott.M.Haan(--nospam--at)poa02.usace.army.mil> wrote:


Can you use horizontal reinforcement in the top of a footing to resist the
pop out of a concrete tiedown anchor rod?  I  talked about this idea  with
an intelligent engineer and he said it can't be done.

I drew a free body diagram of a pop out cone with the reinforcement
developed in the cone and with the shear friction parallel to the cracks
with the vertical of shear friction component cancelling out the upward
force and the horizontal component cancelling out.  I'll e-mail a .pdf of
the solution if someone wants to look at it and tell me where it goes South.

He said the tension is acting vertically across the inclined crack failure
plane, and you've got the shear component parallel to the crack and tension
component perpendicular to the crack, and that the shear friction  formula
in ACI 318 for reinforcement at an angle to the crack only applies to force
component parallel to the crack.

This is where my head starts hurting assuming the free body diagram is
inappropriate, couldn't you still increase the amount of horizontal
reinforcement across the crack to cancel the horizontal component of tension
perpendicular to the crack and add more shear friction for the component
parallel to the crack ect...etc....

I don't believe horizontal reinforcement couldn't clamp concrete from
popping out with enough horizontal reinforcement clamping the pieces
together.


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