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RE: Back to ACI App D and Punching Shear

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When I can't get the concrete anchor formulas to work for tension - I put a
bearing plate at the bottom of the member and check for punching shear or lap
the anchors to vertical reinforcement with enough development length on both
sides to develop the tension.

Normally I try a bearing plate in an isolated footing and lap to
reinforcement in pedestal, and use shear lugs or an embedded MC or C shape
for shear.  

ACI 318 appendix D is a pox on the profession. The 2008 provisions were
written with input from Dimensional Solutions which just jacked up the prices
on DSAnchor by the way.  I heard from a good source that there is an Enercalc
module being developed to solve the anchor formulas also.


-----Original Message-----
From: refugio rochin [mailto:fugeeo(--nospam--at)gmail.com] 
Sent: Wednesday, April 16, 2008 3:39 PM
To: seaint(--nospam--at)seaint.org
Subject: Back to ACI App D and Punching Shear

Now, I am a little more confused, but using what I have come up with as a
solution.  Now I am writing to get some kind of assurance.  I still have my
doubts.

So, the whole scenario, is that I have to put a tie-rod protruding from a
concrete beam, to take 144 kips ultimate value, the concrete beam spanning
4'-0" between soldier beams.  I am assuming a 2'-0"
square concrete beam, spanning in between W24 soldier beams.

So, if I look at this whole thing with punching shear calc, then it far
exceeds the capacity.  If I look at it using Appendix D, it doesn't work at
all.  Why are these two methods giving me such different answers?  I think
the old UBC method is more intune with the punching shear calculation than
the new calculation.

Does the reduction in capacity have anything to do with tension on the side
of the concrete breakout cone?  Or do engineers agree that using the punching
shear instead of the Appendix D is a proper calculation in such a case?  The
tension rod has a 6"x9" plate at the thrusting end.

Best Regards,
Refugio

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