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Re: EOR(Kansas City Hyatt Walkway Failure)

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>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 
cartoons--not designs.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)