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Re: ACI 318 - request for comments for improvements

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A two part response:

First, regarding code complexity.  I do not feel the ACI code is all that
complex.  The only real comments I would add (or second) would be better
explanation of some of the variables, consistency of variables throughout
the code, and better, clearer diagrams, and maybe a better index and cross
referencing of related provisions.

Second is regarding design in concrete.  I have read many of the responses
with interest.  Yes, a concrete structure can be more complex to design, but
I can honestly say this has never influenced our decision to utilize one
material over another.  The fact is that the choice of a structural system
is dependent on too many other important variables, suitability of use, span
and load, floor to floor heights, fire-rating, final finishes, geometry and
lateral systems, economics, and so on.  Each material has definite strengths
and weaknesses, the goal being to select the most appropriate system for the
project.

The inherent continuity of concrete systems adds complexity to the design
process.  Any indeterminate system adds complexity to the design process. Is
designing a flat plate or P/T flat plate considerably more complex than
properly designing a composite steel floor system? Not really. (IMHO)  Is
designing a steel moment frame with "special" detailing or an EBF frame
system much different than designing a concrete moment frame or shear wall
system?  Not really.
For an engineer to have a preference, I think it really comes down to
familiarity and office resources.  A firm with extensive experience,
software, in-house spreadsheets, a good grasp of the detailing and "best"
approach to designing in either material would not, in my opinion, base
material and systems selection on what was "easier".  The fact is some firms
are more "productive" (i.e. more comfortable, more experience, better
equipped) designing in one material over another, and this may have an
impact on their first choice or recommendations of structural systems.  It
typically will influence the types of projects pursued.

The trade associations should provide more support to building familiarity
than questioning code complexity.  Provide the ACI design manuals bundled
with the code with the costs offset by the producers.  ACI should look at
the historic sales numbers, how many of the design manuals are you actually
selling in comparison to the number of code books?  If the typical office
only has the code, it is no wonder concrete seems infinitely more complex.

Otherwise, the choice of concrete is dependent on economics more than any
other factor.  Construction timeline, costs, and associated project costs
and project requirements will dictate the choice of materials.  After all,
designing a composite steel floor system is more complex than designing a
non-composite system, but we still do more composite than non-composite.

Paul Feather
San Diego
----- Original Message -----
From: <Scott.Maxwell(--nospam--at)aci-int.org>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, June 08, 2001 12:14 PM
Subject: ACI 318 - request for comments for improvements


Greetings:

I would like to see if you would provide us with a little assistance, which
ultimately could end up helping yourself.

ACI has heard and received comments about the complexity of the ACI 318
concrete code.  Some surveys have suggested that more structural engineers
prefer to design in steel than in concrete.  Some use these surveys to
conclude that the ACI 318 code is a major contributor to this preference.
This concern has been expressed to ACI by several of the major concrete
trade associations.

We would like to conduct a survey to attempt to determine what areas of the
code need improvement or clarification (note, I hesitate to use the word
"simplification").  The hope is to get some feedback on how to improve the
318 code to make it more useful and user-friendly.

We are currently at a loss, however, as to how approach this problem,
especially since the code itself is rather large, making it difficult to
focus in on particular problems.  We are hoping that you might be willing
to offer some ideas.  For example, what areas of the ACI 318 code do you
find too complex or burdensome to use?  Basically, we are looking for you
to share with us some of you experiences and thoughts on using this code.
We hope that this will help us craft a more through survey that will allow
us to determine how we can make the ACI 318 code a better, more
user-friendly document.

Thanks,

Scott

_____________________________________________
Scott E. Maxwell, PE, SE
Structural Engineer

ACI International (American Concrete Institute)
38800 Country Club Drive
Farmington Hills, MI  48331

T:  (248) 848-3829
F:  (248) 848-3720
E:  Scott.Maxwell(--nospam--at)aci-int.org


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