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RE: New LFRD/ASD Steel Code (Was: Any Young Engineers Out There?)

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I agree with Scott's comments below.  You can calculate actual service
load stresses the same as always, but the allowable stresses will need
to be determined under the new code once it is adopted via the building
codes.  And as an "old engineer" that hoped to retire before having to
learn LFRD for steel design, it looks like it will be just as easy to
design per LFRD as per ASD under the new code (or perhaps, just as hard
to learn to design per ASD under the new code as it is to learn to
design per LFRD). 

It is my opinion that codes for all construction materials should
maintain some basic allowables for design or analysis per ASD.  We
should never lose the ability to determine "actual stresses" in a
structural member under applied loads, and we should not lose sight of
what are appropriate allowable stress ranges when doing such analyses. 


William C. Sherman, PE
(Bill Sherman)
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)cdm.com

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
Sent: Tuesday, January 24, 2006 12:53 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Any Young Engineers Out There?

Ya, but they will be taking it off that shelf in the not so distant
future.  This difference this time is that future model building codes
(i.e. starting with 2006 IBC, I believe) will not longer reference the
1989 AISC ASD spec as "permitted"/"legal" design.  All current codes
that I aware of that are in effect (i.e. legally adopted by local
jurisdications) still reference the 1989 AISC ASD spec (sometimes they
also reference the Supplement 1 to the ASD spec that was officially
released in December 2001 although it did not really modify all that
much) along with a version of the LRFD spec.  Thus, you can right now
"legally"
design using the 1989 ASD spec.  This is largely due to AISC not
updating the ASD spec and not being able (or wanting to...maybe) "kill"
it from the model building codes.

That is until now...

Now they have an updated spec that updates both ASD and LRFD and that is
what will be referenced in future model (i.e. IBC) building codes.  And
when that happens, we will all be "forced" (although I have no doubt
that some will continue to use "old" ASD) to use the new spec.  Now, it
will not happen right away cause even once a model building code adopts
the new spec (which I believe that the 2006 IBC has done), it takes time
for many local jurisdictions/states to adopt that model building code.

So, enjoy your reprieve and relish your last, limited time with 1989 ASD
(and thus "Green Book") spec.  You will likely be delving into the 2005
ASD/LRFD spec relatively soon, be that either in the form of a free PDF
from AISC or in your brand spaking new 13th edition AISC manual
(assuming that they ever ship them...sorry Charlie...could not help
myself <grin>).

Now, the interesting question I think is: how many people will make the
switch to LRFD when they are force to learn the new 2005 ASD/LRFD spec?
After all, the only really difference between "using" ASD and LRFD will
be whether or not you want to put load factors on your load calculations
on the "demand side".  The "capacity" side of the equation will be
virtually identical.

Regards,

Scott
Adrian, MI


On Tue, 24 Jan 2006, Polhemus, Bill wrote:

> Here's the question that I want to see answered...and mark my words, 
> it will probably be asked before a year has gone by:
>
> "How many engineers here--regardless of age--took one look at the new 
> Thirteenth Edition AISC Manual of Steel Construction, put it up on 
> their bookshelves and went right back to the Ninth Edition?"
>
> (N.B. It's gonna take forty years traveling in the wilderness, like 
> Moses and the children of Israel, before the last vestiges of the ASD 
> Idolatry are snuffed out).

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