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# RE: Matrix Stiffness Method with Spreadsheets

• To: seaint(--nospam--at)seaint.org
• Subject: RE: Matrix Stiffness Method with Spreadsheets
• From: Tripp Howard <tripphoward(--nospam--at)yahoo.com>
• Date: Thu, 19 Jun 2003 11:00:59 -0700 (PDT)

If all you're interested in is analyzing simple beams, you can use the moment area method and not be bothered with all the matrix analysis and ctrl-shift-enter stuff.  This is the method that the beam analysis components in Enercalc use.  I've created a spreadsheet to do simple beams with point, uniform and trapazoidal loads.  It calculates moment, shear and deflection.  The method involves breaking the beam into 100 or so pieces and performing analysis on each segment.  I believe Blodgett has a section on how to do this.  Also, there used to be a spreadsheet on Structuralist.net that did this, but I just looked and couldn't find it.  I think this method could also be used for continuous beams, but I havn't tried to do that yet.

Hope that helps.

Tripp Howard, P.E.

Bill Allen <T.W.Allen(--nospam--at)cox.net> wrote:
Ed-

I agree with all of your points, especially for small models (single bay
braced and moment frames, etc.)

You only need to learn two new functions in Excel:

MINVERSE and MMULT

These two functions take the inverse of a matrix (Excel calls 'em
arrays) and MMULT multiplies two matrices. Once you highlight the
regions you want to operate, then, instead of just hitting the "enter"
key, hold down the "control" and "shift" keys while you press the
"enter" key. Some wizards have suggested that it helps to close one eye
and stick your tongue out just right, but I have yet to see the benefit
of this.

Second, you can learn enough about matrix structural analysis in a
weekend if you get the book creatively titled "Structural Analysis", by
Russell C. Hibbeler, 3rd Ed. Chapters 13, 14 and 15 are all you need to
study.

Happy vectorializing!

Regards,

T. William (Bill) Allen, S.E. (CA #2607)
V/F (949) 248-8588
San Juan Capistrano, CA

:-----Original Message-----
:From: Ed Tornberg [mailto:edt(--nospam--at)blazerind.com]
:Sent: Thursday, June 19, 2003 8:17 AM
:To: seaint(--nospam--at)seaint.org
:Subject: Matrix Stiffness Method with Spreadsheets
:
:
:I'm tired of the inefficiency of transferring data back and
:forth between my FEA program (RISA) and Excel. I have to use
:the FEA program to get the member results for things like
:continuous roof or floor beams, and have to use the
:commentary you need to have in the calcs. Is there a simpler
:way for "simple" things like 2-D continuous beams?
:
:Can you write the matrix stiffness method into Excel? Are
:there any references for this?
:
:Or what would be the best FEA program to integrate with Excel?
:
:got tired of it's tendency to crash if you put too many
:spreadsheets or other program objects into it.
:
:Ed Tornberg, PE
:Blazer Industries, Inc.
:
:
:
:
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