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RE: Q: COMPRESSION Force On Anchor Bolts/Rods

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Basically you design the compression rod the same as you design the tension
rod.  You have to develop a shear cone downward.  If your anchor bolts have
a nut at the bottom you would have to have enough material below the bolt
to develop a shear cone.  On the other hand, if you insure that there is a
nut at the top of the concrete that is in bearing, then you can start your
shear cone from that point.  The difference is that now the compression
load has to include the weight of structure which simply means that the
anchor bolt is resisting more load in compression than it is in tension.

Many poles will have leveling nuts and questionable grout or no grout.  If
the leveling nuts are left in place, then the compression load is going to
be resisting by them and should be taken into account.

Neil Moore, S.E.
neil moore and associates


At 09:32 AM 12/12/2001 -0600, you wrote:
>FWIW, I do not think that ACI 318, Section 12.3 really applies. Note that it
>mentions specifically "development of deformed bars in compression." A
>smooth anchor rod is NOT the "deformed bar" by any stretch, IMO.
>
>Typically the "development length" of an anchor rod is not relevant in the
>same way that ACI 318 defines development length. The smooth bar is
>considered to have no significant contribution to the pullout capacity of
>the anchorage.
>
>
>
>William L. Polhemus, Jr. P.E.
>Polhemus Engineering Company
>Katy, TX, USA
>Phone (281) 492-2251
>FAX (281) 492-8203
>email bill(--nospam--at)polhemus.cc
>
>-----Original Message-----
>From: Padmanabhan Rajendran [mailto:rakamaka(--nospam--at)yahoo.com]
>Sent: Wednesday, December 12, 2001 8:36 AM
>To: seaint(--nospam--at)seaint.org
>Subject: Re: Q: COMPRESSION Force On Anchor Bolts/Rods
>
>Bill et al,
>
>This is what I do, when it comes to designing
>anchorages in compression. Calculate the cevelopment
>length required to transfer compressive forces per ACI
>318, Section 12.3. I am comfortable with this approach
>
>
>
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