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Re: Slender walls

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It would seem to me that this section would not apply to walls with
horizontal concentrated loads.  Section 14.8.2.1 specififcally states
that:

"The wall panel shall be designed as a simply supported, axially loaded
member subjected to an out-of-place UNIFORM lateral load, with maximum
moments and deflections occuring at midspan." (emphasis added on my part)

Thus, it would appear that you can not use these provisions for walls with
a concentrated horizontal load.

As far as the wall being prestressed, I don't see anything in the
provisions that would disallow the use of this section as long as you are
meeting the various requirements, such as the vertical stress due to both
gravity loads AND THE PRESTRESS not exceeding 0.06f'c at the midheight
section and assuming that prestressing force has no eccentricity (this is
nothing explicitedly state about this but it seems that moment due to
prestressing could make it such that you no longer met the requirements of
section 14.8.2.1).  The second item above is a little speculative on my
part and could be a non-issue (i.e. eccentricity of the prestressing could
be permitted), but the first item would be something to look at.  The key
in my mind is that the prestress load would have to be added to the
gravity loading into the Pu and Mu and not "neglected" in any way.

I would suggest that you take a look at the referenced publications
indicated in the commentary (refenence 14.5 and 14.6) if you can get a
hold of them.  If you still have questions, then you can try contacting
ACI at their technical inquiry email address (techinq(--nospam--at)aci-int.org).  You
will likely get a similar or weaker answer for them since they are not
really there to give hard and fast interpretations of provisions in
technical publications but rather to point you in the right direction so
that you can find the answer yourself.  You could also try contacting Neil
Hawkins or Sharon Wood since they were two of the three authors of
reference 14.6.  In the mean time, I will use some of my contacts to see
if I can get a more solid opinion on the prestressing issue.

HTH,

Scott
Ypsilanti, MI


On Thu, 10 Oct 2002, Bogdan Dumitrascu wrote:

> Hello everybody.
>
> Can someone tell how should we understand the provisions in 14.8 (ACI 318-02) regarding slender walls?
>   a.. what about prestressed slender walls?
>   b.. what about walls loaded with concentrated horizontal loads?
> Thanks in advance.
>
> Bogdan Dumitrascu
>


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