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Re: 3000 psi concrete and special inspection

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Scott Maxwell wrote:

Dennis,

Here is where I pull out a tired old phrase of "be careful what you ask
for".  You have in the past (including one of the messages on this thread)
talked about how you liked the fact that the UBC reprinted (typically with
modifications) the ACI 318 provisions directly in the UBC code and in the
same breath complained about how the IBC no longer does this, which
requires engineers to buy both the IBC _AND_ ACI 318.  The consequence of
this is that the 1997 UBC (and presumably ealier editions) neglected to
include Chapter 1 of the ACI 318 when they reprinted ACI 318-95.  If they
had, then the provision of ACI 318 that directly excludes its application
to slabs on grade (in the building or not) would have been part of the
1997 UBC.  As a result of it not being included, it is not clear at all if
Division II of Chapter 19 of the 1997 UBC applies to slabs on grade or
not.

I will point out that it is VERY CLEAR in the case of the IBC.  You are
NOT required to use ACI 318 for slabs on grade when using the IBC (you
still can, but the code does not require it).

So, in the process of getting everything included on one book (not quite
as you still need the AISC specs and the NDS, I believe), the 1997 UBC
lost some of the intent of ACI 318.  So, be careful what you wish for...

Scott
Adrian, MI


Scott,
I love our discussions and debates - they lead to so much enlightenment (I hope for others as well). Let me make a couple of corrections in your post above. First, I have "never" offered comment specifically to the IBC since I am not familiar with the code other than the IRC having read the drafts from the BSSC TS-7 committee which I was a member but had nothing worthwhile to offer. However, what I did say was that prior to the 1994 UBC, material design methodology was embedded in the Uniform Building Code. This did not negate reference to ACI 318 or AISC (for steel) or any other design methodology in full or part. To be more specific, the "intent" trail was never included in the UBC and in most cases this did not do away with the need to obtain the full material documents. However, what it did do was to define the narrow scope that some of us needed in the type of design we practice. With the adoption of the 94 or 97 (I know forgot which), each section of the code for Concrete, Masonry, Steel, Wood etc. were only referenced to the full documents which required the practitioner to pay for the entire document when he or she only needed the "flow-chart" logic for one or two sections. In my opinion, this was done to promote revenue rather than to serve the practitioner. I never had a problem paying for what I used, but I certainly resented throwing out 95% of a document that I would most likely never use.

The problem today is not whether the original documents are embedded into the code or simply referenced - it is that the logic trail fails to serve the community. If I try to simplify this, I would have to use the analogy of a program. Computer programs follow logic - "if-then", "if-then-else" etc. The issue brought up by Steve Gordin and Acie Chance both identify the problem of ambiguity - the lost trail back to the original intent of the code.

In my opinion that before the legal rhetoric is written (shall, may, should, will etc.), a logic trail comprised of all work getting from point A to point B should be clearly defined. By doing this removes the ambiguity and makes the intent clear. There is no reasonable explanation for why this has not been done - at the least a "library" containing all committee meeting notes, input from engineers serving these committees and the adoption of ideas that result in the final rhetoric of the code MUST be documented and a logic flow chart created to track back to the intent. If something changes, then there must be a logical position on this chart defining where and why the change was adopted.

You see, the committees are dynamic. When people leave and new people come to the table, information relevant to the creation of what is to become code is displaced or lost. This is why the SEAOC Seismology Committee could not clearly answer questions relative to light-framing and its adoption under the methodology used for all other materials. We who practice light framing understand when it is appropriate to fully comply with the code and where the requirements of the code are simply unreasonable. As a contract plan checker, I have yet to have a residential structure (including multi-residential structures) submitted based on full compliance to the 97 UBC. Furthermore, this also accounts for the change in opinion by SEAOC as to what should or should not be designed to full-compliance.

We have had this debate many times - to the point where I might have won the battle and lost the war. However, here is the case where we are debating where and when UBC section 1921 is to be used or where section 1922 is adequate. The line of distinction is not defined and there is a lack of logic trail. This has nothing to do with whether ACI 318 was fully embedded into the code or simply referenced in part. This is an economic issue to raise revenue not to serve the profession.

Okay - go ahead and flame :-)

--

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

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