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RE: RISA-3D Steel WF Torsion

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Bill,

If you could send me your model I would be happy to look at it.

Thanks,

Bruce Bates
RISA Technologies



  _____  

From: bill(--nospam--at)polhemus.cc [mailto:bill(--nospam--at)polhemus.cc] 
Sent: Thursday, April 16, 2009 1:57 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?


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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Try checking your frame model and =
make
sure that all columns supporting the beams which are failing have the =
correct
support condition (fixed or pinned). I had a similar problem when I =
forgot to
put a support condition to column below a =
beam.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> =
bill(--nospam--at)polhemus.cc
[mailto:bill(--nospam--at)polhemus.cc] <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Thursday, April 16, =
2009
1:57 PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">seaint(--nospam--at)seaint.org</st1:PersonName><br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RISA-3D Steel WF =
Torsion</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>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 &quot;statics-based&quot; =
puke).<o:p></o:p></span></font></p>

<p><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>When I
look at the &quot;Shear Check&quot; plot on-screen, I'll see a lot of =
failures
of wide-flange members (mostly beams), many with rather large
&quot;understrength factors&quot; (if you will; I guess we used to say
&quot;overstress&quot;), between 3.0 and =
4.0.<o:p></o:p></span></font></p>

<p><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>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).<o:p></o:p></span></font></p>

<p style=3D'margin-bottom:12.0pt'><font size=3D3 face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt'>Any thoughts?<o:p></o:p></span></font></p>

</div>

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