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Re: SAP2000, RISA3D, and STA

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-----Original Message-----
From: Roger Turk <73527.1356(--nospam--at)compuserve.com>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Tuesday, December 16, 1997 8:54 AM
Subject: SAP2000, RISA3D, and STA
 
While I agree with a lot of your comments, I think you are carrying this thing
way too far. Based on your own recommendations, I don't see how you could 
even use a spreadsheet program. I certainly believe the modeler should do 
some spot checking (global equilibrium) mainly to check his/her input and to 
compare the results from another program if possible. Since computer programs 
mostly use numerical results, they will seldom have the same results as a 
classical solution. You probably write your own programs to solve your 
engineering problems (let me guess, DOS right?) or worse, do most of your 
calculations by hand (still!). This probably puts you in the 98th percentile of the 
general structural engineering practice. I have not run across any software 
author that "seals" his application nor would I expect to. This is clearly the 
responsibility of the structural engineer of record. 
 
One exception to the above is in regards to new software offered to the public.
A colleague of mine recently got a beam program. In doing his due diligence 
to check the software, he modeled a simple beam with a single cantilever. This 
beam had a single concentrated load located at the very end of the cantilever. 
The results of the showed no reactions, moments or shears. Once he moved the 
concentrated load slightly off the end of the cantilever, he got the results he was 
expecting. I'm not going to mention the software vendor's name here since this 
is not first hand information and because I believe the problem may be solved by 
now. This may be an approprate forum for us to post "bugs" so that: 
 
1.    We are aware of the problems. 
2.    The vendor may provide fixes in a more expeditious manner.
3.    The vendor may publish the reasons why a user may be using the software
        incorrectly.
 
Regards,
Bill Allen 

 
>From that time on, I have been very skeptical of computer programs that do
>not provide the source code in readable form, where the programmer and
>his/her qualifications are not given, and, for structural analysis and design
>programs, where the structural engineer responsible for the program does not
>seal the listing and the users' manual.  After all, it is the person writing
>the program that is doing the analysis and/or design, not the person
>inputting data.  (Any clerk can input data from a coding sheet.)
>
>A. Roger Turk, P.E.(Structural)
>Tucson, ******* ******* ***
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