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Re: SAP SHELL DESIGN

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On May 20, 2007, at 10:44 AM, hossein mardanlo wrote:

It seems you have got a lot of negative energy from someone recently!
It sure does, doesn't it?

Anyway, I have been using applied mechanics for many years successfully, maybe more than you!
It's possible--I wouldn't bet on it.

And of course I always will need to learn more, even though someones like you may doesn't need for more learning! But using new methods are always necessary. I wish You could answer my question!
Your question really had no answer, since you didn't specify what kinds of suggestions you were after. SAP2000 does what it does-- nothing to suggest. SAP 2000 is like ANSYS or NASTRAN or other general purpose FEA software--they do analysis, not design. Design is an engineer's job. Sometimes you'll find program features that seem to mimic design, but they're usually doing iterative analysis based on user-specified criteria. Codes like the AISC Code or the Boiler Code rely almost exclusively on manual calculation and proportions for details which have given satisfactory service.

That said there's not a whole lot of structural code provisions specifically addressing general shell theory. I don't use SAP2000, but from what I read the Code provisions it incorporates are aimed at framed structures. The design methodology in the ASME Codes is based on shell theory, and there are areas in those Codes that are written around the use of FEA output, but the loading and service doesn't apply for all fields of engineering. It's not too tough to apply equivalent standards to shell element results for metals, once you know enough mechanics to understand the basis of Code provisions. ANSYS, for example, has no AISC Code post processor, but it's fairly simple to do the arithmetic with a spreadsheet using tabular output if you're dealing with plate structures or shells. If there are programs which do anything other than simple Div 1 design (like Caesar or Codeware) I'm not aware of them. ANSYS will provide primary, secondary and peak stresses, for Nuclear Code assessment, but it's really doing an analysis task, not design, and it should only be used by engineers who really know their stuff, because it's easy to confuse things.

You didn't mention whether your plant design problem involved metal or concrete. I daresay the ACI has provisions for shell like cooling towers or domes. There may even be software which does design tasks like re-bar placement but I don't do concrete, and I don't keep up with it. The ASME Nuclear Code also covers concrete containment vessels, but again, I don't know of software that actually designs these things. Again--it's the engineer who does the design, using FEA results.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/



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