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RE: Staad: Master/Slave Joints

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John,
 
The last time I attempted to use the master/slave option in STAAD to model a
rigid diaphragm I spent an infinite number of hours on the phone with REI
discussing the obvious disconnect between the intent of that command and
what I was seeing on the output side of things.  After many conversations I
finally got someone at REI to admit that it was not handling rigid body
rotation correctly (and I believe this was posted on their web site at one
time).  I believe the version I was using was STAAD/Pro Release 3.1, Build
1002.  I do not know if this has been corrected in STAAD/Pro 2000, Build
1007.  The other option is to place infinitely rigid truss members (with no
self-weight being applied) between joints to simulate "immense ridgity"
where you need it.
 
Hope this helps....
 
Robert C. Rogers, PE 
robert.rogers(--nospam--at)woolpert.com 

-----Original Message-----
From: Connor, John A NWK [mailto:John.A.Connor(--nospam--at)nwk02.usace.army.mil]
Sent: Tuesday, August 08, 2000 5:31 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: Staad: Master/Slave Joints


According to Staad's user manual, you can use the master/slave joints to
model a rigid diaphragm.  Does anybody know its limitations/assumptions?
 
I'm playing with an example, and the results do not make much sense.  I made
a 3d model for a 3 story structure.  I have moment frames evenly spaced in
each direction.  I gave each frame a different stiffness.  Some frames are
all W10's and others are W12 members.
 
Using the master/slave to make a rigid diaphragm, I would expect that each
frame would have the same deflection, and the differences between each frame
would be their stresses.  However, the results are showing each frame with
varying deflections.
 
Anybody have any insight to this?
 
Is there a better way to make a 3d model?   (please don't say..."don't use
Staad").
 
Thanks,
John Connor, PE
Kansas City, MO


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