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RE: Interpreting Analysis Results

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Bill
 
     The Mxy term is a warping moment.  I always add it to Mx and My as it will be in the same direction as the moments Mx and My along one of the four faces.  This is probably a little conservative.  This is also the approach suggested by RISA to account for this moment.
 
Acie Chance 

 
 Original Message-----
From: Bill Allen, S.E. [mailto:T.W.Allen(--nospam--at)cox.net]
Sent: Friday, December 24, 2004 11:12 AM
To: seaint(--nospam--at)seaint.org
Subject: Interpreting Analysis Results

I’ve just modeled my first mat foundation using STAAD Pro and the foundation support option. I’m not using their foundation module, just the feature within the plain vanilla version which allows me to specify a modulus of subgrade reaction and the program applies the appropriate spring support at each node. Nice feature.

Anyway, the results I get are forces at the center of each plate. I get two shear components, Qx and Qy in psi and three bending components, Mx, My and Mxy in in-lbs/in. I know what to do with the Qx and Qy terms; I would compare these values with phi*2*sqrt(f’c). I know what to do with Mx and My. These are pretty straightforward.

The value that has me a little baffled is the torsion term, Mxy. It appears to me that I need to do some sort of Tc/J calculation and add this value to the Qx and Qy term, but I’m not certain.

Thanks in advance,

T. William (Bill) Allen, S.E. (CA #2607)

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