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Re: Structure Magazine - Computers and SE Judgement article

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>I just finished Richard Parmalee's article entitled " Have We Let Computers
>Replace Structural Engineering Judgment". 

I've spent a lot of time putting numbers to other engineer's 'judgement' 
and found any number of instances where 'engineering judgement' was 
simply bad judgement--poorly thought-though hipshots to gross ignorance 
of first principles. And I've taken some heat from the hipshooters 
because I like to put my judgement calls into numbers when that's at all 
possible. Good judgement means backing up a qualitative assessment by 
doing the numbers. Presuming to use 'judgement' instead of doing the 
numbers is as foolish as accepting a stress plot uncritically. Or as 
foolish as launching into a discipline (dynamics in particular), armed 
with nothing but FEA software and only the sketchiest notion of the 
physical principles involved.

My own take on software-abuse is that too few people cross check their 
numbers. I've heard people rail about the need to understand algorithms 
and programming techniques, but you don't need to understand C++ to check 
results for consistent static or dynamic equilibrium. An engineer once 
pronounced a particular program 'buggy' because his version gave him 
reasonable answers while my answers weren't. A quick statics check of 
reactions against applied load showed that his reasonable answers were 
only reasonable because much of the load was missing. Turns out his 
version of SPSTRESS or STRUDL misinterpreted the loading, and his 
'judgement' might've gotten him into real trouble.


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)
http://www.skypoint.com/~chrisw