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RE: RISA-3D Steel WF Torsion

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It generally does not take much to cause torsion to blow up a wide flange in shear.  I would surmise a guess that it is likely torsion (I had a similar problem).
 
You might try sending the model to the RISA support staff.  When I had a similar issue (members failing in shear for reasons that I could not see), I sent them the model and they were able to point out/confirm that it was a torsion issue.  They have been very helpful in the past (this assumes you have a current support contract).
 
Or I might even be able to take a look at it if you want.
 
Regards,
 
Scott
Adrian, MI


From: bill(--nospam--at)polhemus.cc [mailto:bill(--nospam--at)polhemus.cc]
Sent: Thursday, April 16, 2009 4:57 PM
To: seaint(--nospam--at)seaint.org
Subject: RISA-3D Steel WF Torsion

I'm getting some anomalous results from a rather complicated steel frame run on RISA-3D. I'm doing RSA with this, and I have already noticed some peculiar results (at least for this "statics-based" puke).

When I look at the "Shear Check" plot on-screen, I'll see a lot of failures of wide-flange members (mostly beams), many with rather large "understrength factors" (if you will; I guess we used to say "overstress"), between 3.0 and 4.0.

But when I look at the specifics of a given member, I don't see any large shears at all. I'm inclined to think it might be a torsion problem showing up, but even the torsion doesn't seem that great (although it is present).

Any thoughts?