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RE: ASD vs. LRFD

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I wasn't going to reply but with two topics in one that I have a strong
opinion about (and what don't I have a strong opinion about?) I can't help
myself:
Autocad:
I'm glad I waited between R12 and R2000 ADT2. I've worked with the versions
in between, but did not upgrade until the latest. I believe Autocad 2000
ADT2 (Architectural Desktop 2) is the best of the bunch. Before I get
flamed, let me preface by the fact that if you were using S8 add-on, ADT2
loses some of it's punch, however, it makes up for it by finally completing
the concepts and value of Model and Paper space which, until this version, I
avoided like the plague. With Layout sheets (similar to worksheets in an
Excel Workbook) it is very easy to understand the relationship of model
space and how to gain the most advantage in Paperspace.
The integration of a multiple drawing format (able to open multiple drawings
in the same session and the ability to drag and drop between different
drawings is invaluable to me. Add to this the integration of VBA and a
healthy user supported newsgroup - ADT2 is a real winner.
What makes it different than the past versions is the change from a vector
based system to an object based system. This lends to easy automation as
well as the ability to define plotting features to virtually every line or
object drawn.
Plotting is a nightmare when first learning, but the complexity is justified
by the extreme flexibility of what you can do with this release. Mind you,
many of the features were available in past versions (at least those that I
like) but were hidden deep in the menu structure. One example is the ability
to set shading or screen percentages which was available in R14 if you knew
to get into HPConfigure and set the colors to a percentage of opaqueness.
The S8 detailer is still there in ADT2, but you have to dig for it and it is
not supported by documentation. Still, it is part of the package and works
just as well as it did in S8. Auto framing features are lost in this
version, but 3D is now much easier to work with.
All in all - it is the best Autocad that I have worked with since 2.5.

LRFD in Wood.
It may have it's benefits but the effort to search for all of the factors is
a royal pain for whatever benefits that you gain. I attended the seminar in
City of Commerce (in fact I spoke there) and am frustrated with the
complexity of setting up LRFD tools. It's a lot of work and I'm not sure the
benefits are worth the effort. Mike Cochran, SE explained it at the seminar
as establishing the outside boundaries of wood performance and then using
both ASD and LRFD to find solutions that stay within the performance limits.
In residential design, I am more worried about stiffness in gravity load
members than economics of the sections. I look close at deflection limits to
determine if a floor is going to be bouncy and I look at deflection limits
to be sure that the architects visual lines stay straight. However, this
does not seem to be the purpose of LRFD. It seems best applied to wood
products which are predictable such as manufactured wood products - in which
case, proprietary software may be the answer.
In lateral design, I am frustrated with fine tuning the stiffness of
shearwalls to such a degree that no contractor can afford to build it so
perfectly.

I think there is a lot to study in LRFD for wood and for what it is worth at
the moment - it seems to be more trouble than it is worth.

Dennis S. Wish, PE

-----Original Message-----
From: Bill Allen [mailto:Bill(--nospam--at)AllenDesigns.com]
Sent: Wednesday, April 26, 2000 9:43 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: ASD vs. LRFD


Speaking of short memories...

ACAD R12 was built for D(ead) O(perating) S(ystem).

yes, R13 did suck and cost me a L O T of money in production time.

R14 works well in Windows. From my personal experience, the first time
AutoCAD and Windows worked well together was ACAD R13C2 and Win95B. But,
ACAD R14 and WIN98 works well enough for me that, for the first time that I
can remember, I don't have the Latest and Greatest (tm) versions on my
machine.

Of course, the above is all my opinion and should be considered as such.

Oh yeah, I design using ASD. In fact, I use ASD in masonry and wood, too.
I've also been known to use WSD in concrete design when I am more concerned
about cracking and deflections (i.e., service performance) than I am in
maximizing the strength of a section (which, for me, is most of the time). I
do admit to using LRFD in light gage steel design only because the 1996 AISI
Cold Formed Steel Manual (the first one I've used in 20 years) is LRFD
based. Sooo...I calculate section properties and fastener strengths in LRFD
terms then divide by Omega to get the ASD values. Sigh....

Regards,

Bill Allen, S.E. (CA #2607)
ALLEN DESIGNS
Laguna Niguel, CA
http://www.AllenDesigns.com


||-----Original Message-----
||From: Fountain Conner [mailto:fconner(--nospam--at)pcola.gulf.net]
||Sent: Wednesday, April 26, 2000 7:47 AM
||To: seaint(--nospam--at)seaint.org
||Subject: Re: ASD vs. LRFD
||
||
||'Sells more books, dude.
||
||It's like ACAD R12.  Autodesk finally came up with a *great*
||product and
||couldn't stand it.  Consequently they produced and marketed a vastly
||inferior R13 which people were coerced into buying.  It was
||soooo bad that
||when R14 came out, people with short memories tho't R14 was
||the greatest
||thing since sliced bread.
||
||My 2 cents.
||
||Fountain E. Conner, P.E.
||Gulf Breeze, Fl. 32561