Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

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

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Bill:

I agree his logic does not impress me either.  :-(

I kind of figured (after I thought more about the different directions acting on the different bars around the perimeter) that it might not help much.

I will note that section 1910.3.3 does not mean that you need to specifically use 0.75*rhob...it just gives that as a MAXIMUM reinforcement ratio.  To me, you would still use the minimum reinforcement ratios for flexural element per section 1910.5, which are quite a bit less than 0.75*rho.

Of course, you still have to convince the plan checker that it ain't a column but is a "beam" (more precisely a flexural element more so than a axial compression element).  <grin>  Good luck.  FWIW, you could try pointing out the definition of a column in section 1902 and point out that this foundation does NOT primarily "...support axial compressive load."  Most likely won't help...but you never know.

Regards,

Scott
Adrian, MI 

-----Original Message-----

From:  "Bill Allen" <T.W.Allen(--nospam--at)cox.net>
Subj:  RE: The Most Ridiculous Item of the Day (with apologies to Bill O'Reilly)
Date:  Wed Jan 11, 2006 2:33 pm
Size:  2K
To:  <seaint(--nospam--at)seaint.org>

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


 



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ******** 



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********