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Re: 3000 psi concrete and special inspection

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S. Gordin wrote:

Dennis and Scott,

This was exactly my point. I brought the walkway issue just trying to push the argument beyond the rational limit to emphasize that point. For example - it can be formally argued that house slabs with integrated footings are not regulated by 1922.1.1.2, and so, bla-bla... As bad as it sounds, I had experience with plancheckers who would make this kind of an argument. Here, we are essentially talking the difference between the continuous and spot inspections. In my experience, the latter (pre-pour inspection) is forced by most building departments in CA anyway even for the lightest residential footings and even for 2,500 concrete, and is included in the permit fees. The former would be required only for f'c=>3,000 PSI concrete, with inspector present prior during sampling and pouring for an additional fee. At smaller jobs, it makes a lot of difference.

The way I read the code - if 2,500 PSI works for any spread or continuous footing and is fine with the building department - it's OK to use it. On heavily loaded or complex footings, though, I specify 3,000 PSI just to force the special inspection and to have an extra pair of eyes on site.

Steve


Steve,

I disagree as I think you missed the section on structural plain

concrete. Please refer to section 1922 and again specifically 1922.2.4.1

which states similar reference as section 1921 but deals with

foundations and slab on grades.

FWIW, I know of no city that requires the use of 3,000 psi in Southern

California for a slab on grade or a residential (up to three stories)

continuous foundation or pad footings. The only time this becomes an

issue is when there is a moment frame, embedded column or other lateral

load resisting element on an isolated foundation such as a grade beam.

Reread this section to see the difference - it could never be applicable

to flatwork or most of us are really in trouble.

Dennis

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Steve,
I would agree with you on this. However, it would be nice if the authors of the code could be specific or at least lead the community without having to rely upon the purchase of a commentary to act like a "decoder". In this case, "code" does not require encryption - it should be clear and concise defining the intent and the limits of these two section. I am only picking on section 1921 and 1922 of the CBC and UBC because it has led to a discussion that we should not be having.

As a note to Scott: I believe "dickering" on the rhetoric, we agree with one another more so than have our differences. I can only be staunch (or stubborn) on the definition of Code - an adopted and legal document. If, as I think you agree, the code specifically includes all provisions of ACI-318 then you can say that ACI-318 is legally bound into the code and is therefore the law. However, if it is discriminatory, then what is published in the CBC/UBC/IBC etc. takes precedence as this was what was adopted into law by each specific state and further revisions by each municipality.

When methodology is combined in the code as it was prior to 1994 (specific as I understand it to the UBC and not the SBC) there was less confusion as that section of ACI-318 was not simply referenced, but embedded into the code. While it does not specifically stop debate over the intent of the code, it does become law (however ambiguous) by the nature of the rhetoric embedded rather than referenced within the adopted documents.

In short - one is either "all inclusive" or "partially inclusive". This is really the only issues I was "debating" here.

--

*Dennis S. Wish, PE*
*California Professional Engineer
Structural Engineering Consultant

dennis.wish(--nospam--at)verizon.net*
*
760.564.0884 (office - fax)
*

   */This e-mail is intended to be delivered only to the named
   addressee(s) and may contain information that is confidential and
   proprietary. If this information is received by anyone other than
   the named addressee(s), the recipient(s) should immediately notify
   the sender by e-mail and promptly delete the transmitted material
   from your computer and server. In no event shall this material be
   read, used, stored, or retained by anyone other than the named
   addressee(s) without the express written consent of the sender or
   the named addressee(s)./*


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