Subject: Re: EOR(Kansas City Hyatt Walkway Failure)
From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
Date: Sat, 27 Jan 01 22:44:15 -0600
>I fail to comprehend how a design so exotic that it was a near impossibility
>to fabricate or erect could be deemed. "servicable".
It could have been built simply from threaded couplings subsequently
welded to prevent disengagement. Pipe is done this way all the time. The
connection between the walkway cross members could have been made in the
same way by welding a threaded sleeve into the cross members or (better)
by using a fitting or bracket threaded to accept the vertical rod and
made to support the cross-member ends.
The reason this design change was pivotal is that supporting the lower
walkway off the upper walkway is pretty clearly a weaker detail than
hanging both walkways off a single rod. Calculations would have shown
that this detail was weaker than the original and probably have started
people asking questions about the original detail.
It's also fair to say that catastrophes of this sort are a sequence of
events; there is never a single cause. (Think about the Titanic: too few
lifeboat seats, excess speed, no radio watch on the California,
'watertight' bulkheads which allowed adjacent compartments to flood etc)
If any event in the chain hadn't occurred the catastrophe might easily
never have happened or might not have ended in disaster. This whole
thread has listed a number of events showing that the collapse had
multiple causes. The redesign was pivotal since it was the last event in
the chain. I claim that had the rod-to-channel connection design been
checked in anything like a conscientious manner, the weakness would have
been caught and corrected.
>However, the current system of drawing up some pretty pictures, calling
>them design intent drawings, and expecting some poor detailer to make sense
>of them without further assistance is ludicrous.
It's the worst kind of negligence. Like the times when I was in the 6th
grade 'designing' airplanes and boats on a pad of notebook paper when I
should have been paying attention to the teacher. Such things are
Christopher Wright P.E. |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com | this distance" (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)