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RE: The Most Ridiculous Item of the Day (with apologies to Bill O'Reilly)

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The orientation of the member does not make it a column or beam, it is the loads that it sees. I agree that it is a flexural member.

He needs to understand the background of the particular code requirement to know where it should apply. It is interesting that the 1% requirement came out of some research that was done in the 30's. It has to do with the axial load creeping out of the concrete into the reinforcing steel. If the axial load is minimal or almost non-existant, than the requirement should not hold.

Good Luck!

Jim K.

-----Original Message-----
From: Gary Grinstead [mailto:garyg(--nospam--at)structuralstuff.com]
Sent: Wednesday, January 11, 2006 2:04 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: The Most Ridiculous Item of the Day (with apologies to Bill
O'Reilly)


Bill:
1. Use the CBC definition of "Column" from section 1902...."a member with a
ratio of height-to-least-lateral dimension of 3 or greater used primarily to
support axial compressive load".  Since the only reason this would be deep
enough to have a 3:1 ratio is due to the moment from the weight of the lighting
element arm and wind load on the pole, this is not primarily supporting axial
compressive load.  I'm sure the weight of this thing is not such that a pile
would be required.  Therefore it should not be considered a column.

2. Check and see if the Public Works department in your city publishes standard
details for this type (or similar enough) poles.  If so, I'd bet money that
they would not comply with 1% steel either.

Gary Grinstead, SE
www.structuralstuff.com


Quoting Bill Allen <T.W.Allen(--nospam--at)cox.net>:

> Thanks, Scott.
> 
> Unfortunately your argument won't help me.
> 
> First of all, he won't buy the fact that this element is a beam, not a
> column. He says it's sticking out of the ground 2'-6" and "looks like a
> column, so it must be a column". He said if the element terminated flush
> with the ground or paving, he wouldn't have this requirement. Needless to
> say, I wasn't impressed with his logic.
> 
> Secondly, 0.75Rho-b won't help. To make things simpler (for this simple
> mind, anyway), if the section was 21" square instead of 24" round
> (equivalent area), then 0.75Rho-b is 1.3%.
> 
> My next tactic: I'm going over his head. I'll report back with my results.
> 
> Regards,
> 
> T. William (Bill) Allen, S.E.
> ALLEN DESIGNS
> Consulting Structural Engineers
> 
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
> Sent: Wednesday, January 11, 2006 9:23 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: The Most Ridiculous Item of the Day (with apologies to Bill
> O'Reilly)
> 
> Bill,
> 
> I don't think that the code provisions that Sharon pointed out would
> really apply as they are intended for R/C moment frames under seismic
> loads.  While your situation is certainly gonna be under seismic loads, I
> am not sure that it should be classified as a "frame".
> 
> As to the code section the plan checker is referencing, I agree that I
> doubt s/he really meant 1910.16.8.6.  S/he probably really meant 1910.9.1,
> which would land you in the same spot (i.e. minimum steel of 1%).
> 
> Your best arguement comes from section 1910.3.3.  It basically states that
> for flexural members, if the design axial load strength (phi*Pu) is
> smaller than 0.10*f'c*Ag or phi*Pb, then the ratio of reinforcement shall
> not exceed 0.75 of the ratio phob (balanced reinforcment ratio) that would
> produce balanced strain conditions for the sections under flexure without
> the axial load.  I think that is what you might be looking for...
> 
> HTH,
> 
> Scott
> Adrian, MI
> 
> 
>  
> 
> 
> 
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