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RE: Technology and Structural Engineering

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I have heard the same story about Fazlur Khan and I have had similar
experiences with very large industrial equipment support structures on fast
track where I had to design foundations and primary member sizes before the
final structure design.  The optimum use of the computer is making
calculations to verify and refine a design made by an experienced structural
engineer.  This greatly speeds up the design process and eliminates many of
the types of mathematical errors routinely made by humans.  The economy of
time allows more options to be investigated and compared by the experienced
engineer.  It is important to remember, however, that the engineer can think
but the computer cannot; it can only respond with what it has been
programmed to do and those who rely on it to do their thinking will
eventually get into trouble.
With regard to the Seattle Space Needle, I heard the following account: The
design was quite rational, however, even though the engineer knew that wind
loads should control, he was instructed to use a 70 mph wind criteria based
on a report by a local "expert".  The engineer believed that it should be
higher and since he was not given a seismic criteria he instructed his
designer to come up with a seismic factor that would result in the same
overturning moment as a 90 mph wind would produce. This seismic design basis
was not questioned and, later, when higher than predicted winds occurred,
the structure survived; not something your present software would think to
do.
Richard Hess, SE

-----Original Message-----
From: Ben Yousefi [mailto:Ben.Yousefi(--nospam--at)SMGOV.NET]
Sent: Wednesday, August 31, 2005 6:50 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Technology and Structural Engineering

I heard an interesting story, which may be an urban legend. Fazlur Khan,
chief engineer at SOM, designed the Sears tower, which is currently the
tallest building in U.S. before the age of computers, supposedly by
hand. Later on some SOM engineers modeled the bulling on a computer and
ran the analysis. The results were within 5% of the original hand
calculations. Quite amazing for that complicated of a structure.

Ben Yousefi, SE
Santa Monica, CA

-----Original Message-----
From: Gary Hodgson & Associates [mailto:ghodgson(--nospam--at)bellnet.ca]
Sent: Wednesday, August 31, 2005 4:44 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Technology and Structural Engineering

Ralph,
I'm with you-graduated in 1961. I bet if you asked one
of the recent graduates to design a 20 storey building
by hand, they wouldn't know where to start.  Graphic
analysis and moment distribution?  How did they design
the Empire State building?
Gary


On 31 Aug 2005 at 0:50, Rhkratzse(--nospam--at)aol.com wrote:

> I realize that I'm the only person on this list who remembers what
> engineering was like in the 1960s, but the mechanics of producing
> calcs., specs., and drawings were SO much more difficult, and the
> physical quality was so much lower.   I emphasize PHYSICAL quality
> because I DO NOT mean engineering quality.   I mean illegible
> calculations (not spread sheets, etc.), actual cut-and-paste and then
> type and mimeograph specifications, and "Xerox" things one page at a
> time, and erasing your way through the tracing.   Hail, I even knew
> architects who still used ink on linen!   Now we have recent graduates
> who can design 100 story high rises over night, complete with
> color-coded working drawings, having analyzed 100 load combinations,
> but the welds fail in an earthquake.    Oops!   Supposedly the guy who
> designed the Seattle Space Needle just stuck 3 of the heaviest WF
> shapes made into a triangle for each leg and checked it with his slide
> rule ... and it's still there!
>
> Enuf reminiscing.
>
> Wouldn't go back for the world.   :)
>
> Ralph Hueston Kratz, S.E.
> Richmond CA USA
>
> In a message dated 8/30/05 9:35:21 PM, chrisw(--nospam--at)skypoint.com writes: >
> That said, I'm not all that certain that the technology doesn't seem
> to > have made across-the-board improvements in engineering
> productivity, > certainly not in the manufacturing areas where I work.
> I've heard a lot > of claims, usually by software developers, but I
> don't see as much > overall impact in particularly improved design
> methodology, lower costs > or shorter design lead times.
>



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