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RE: Min. Reinf. in large pedestals

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Sorry.

Scott M Haan P.E.
Plan Review Engineer
Building Safety Division 
Development Services Department
Municipality of Anchorage
http://www.muni.org/building
phone:907-343-8183  
fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: Forrest Braun [mailto:fbraun(--nospam--at)bbfm.com]
Sent: Thursday, December 27, 2001 1:09 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Min. Reinf. in large pedestals


Scott and others

If you go back to the original question, I think you will find that this
was an equipment base or mass block and not a compression member.  As
such, the 1% requirement for compression members in ACI/UBC/IBC would
not apply.  In addition, it appears that it is not really a footing
either but would need reinforcing top, bottom and sides to maintain the
integrity of the mass block.

"Haan, Scott M." wrote:
> 
> I didn't write the code [I have made engineer's from Minnesota change
their
> plans because of what it says].  For a caisson it might not be reasonable,
> but then again I am pretty sure off the top of my head they did 1% for the
> local airport caissons even though I did not make them and it probably was
> not required for strength.
> 
> 1% is reasonable for "small" pedestals in most building design.  Where I
see
> it as an issue alot locally is for foundation pedestals for
pre-manufactured
> metal building foundations.
> 
> Scott M Haan P.E.
> Plan Review Engineer
> Building Safety Division
> Development Services Department
> Municipality of Anchorage
> http://www.muni.org/building
> phone:907-343-8183
> fax:907-249-7399
> mailto:haansm(--nospam--at)ci.anchorage.ak.us
> 
> -----Original Message-----
> From: Michael Hemstad [mailto:mlhemstad(--nospam--at)yahoo.com]
> Sent: Thursday, December 27, 2001 9:59 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Min. Reinf. in large pedestals
> 
> Scott, you wrote:
> >ACI 318-99 Section 10.9.1 says the minimum
> >compression member reinforcement is required to be
> >between .01*Ag and .08*Ag.  ACI 318-99 Section 10.8.4
> >says you cannot reduce the minimum compression member
> >reinforcement to .005*Ag in areas of high seismic
> >risk.
> 
> >Scott M Haan P.E.
> 
> OK, let's think about this for a minute.  What would
> you use for Ag?  If it's the 6 meter circle, its area
> is 28.3 square meters and its perimeter is 18.9 m.
> Translating into units that we Americans (and we
> alone) understand, 0.5 percent of the area is 219
> square inches over a perimeter of 61.8 feet.  That
> works out to a #11 bar every 5 inches or so.  I know
> the "T" in the T&S that you have to deal with is more
> than most of ours, but do you really want to do that?
> 
> Area goes up as diameter squared, perimeter only as
> diameter.  At about four foot diameter I usually stop
> worrying about it and throw some reasonable
> reinforcing at it.  Like #6 at a foot.  I would use a
> good deal more reinforcing on the top and bottom
> surfaces, but it will still be a very small
> reinforcing ratio.
> 
> Mike Hemstad, P.E.
> TKDA
> St. Paul, Minnesota
> 
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-- 
++++++++++++++++++++++++++
Forrest T. Braun, P.E.
BBFM Engineers, Inc.
Ph (907)274-2236
Fx (907)274-2520
Anchorage, Alaska
http://www.bbfm.com
++++++++++++++++++++++++++

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