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RE: Cold formed joist design

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David,
Thank you, that is exactly what I was looking for.  I don't think you have
to fax or email anything at this point.  I'll adjust my calcs for the "R"
factor.  Right now the architect is way off on his guess as he is trying to
just double some joist sections and use them for beams.  They are not even
close.  I don't' think that the minor differences in section properties
between AISI and SSMA will make a considerable difference at this point, but
if I need anything further I will let you know.

Thanks again,
Joe

Joseph R. Grill, P.E. (Structural)
Shephard - Wesnitzer, Inc.
Civil Engineering and Surveying
1146 W. Hwy 89A Suite B
Sedona, AZ  86340
PHONE (928) 282-1061
FAX (928) 282-2058
jgrill(--nospam--at)swiaz.com
 


-----Original Message-----
From: David Topete [mailto:davetopete(--nospam--at)yahoo.com] 
Sent: Monday, August 15, 2005 4:20 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Cold formed joist design

Joe,
>From my '96 ed. of AISI manual, the "R" factor is a
reduction factor used in the equation for nominal
bending strength, M_n = R * Se * Fy.  
R = 0.40 for simple span C sections;
R = 0.50 for s.s. Z section;
R = 0.60 for conti. C sections; and
R = 0.70 for conti. Z sections

The name designation (unless it's changed from the '96
manual) is prety basic where it is 1. depth, 2.
section profile, 3. stiffened or unstiffened flanges
(S or U), 4. flange width, 5. thickness in mils.

Ex.:  16CS3.75x135 = 16" C-section, stiffened, with
3.75" flange width x 0.135" thickness.

HTH.  Let me know if you'd like for me to fax or
e-mail to you.

David Topete, SE
SF, CA


--- Joe Grill <jgrill(--nospam--at)swiaz.com> wrote:

> I have a project where there are a few "C" joists
> being used over some
> canopies.  There are a couple of locations where the
> loading is non-uniform.
> I don't have an AISI manual handy and I am trying to
> check these members
> using RISA 3D.  There is a design parameter in RISA
> 3D which is labled "R"
> which has something to do with (I believe as I read
> the help section) with
> whether the top, bottom or both flanges are
> restrained laterally.  RISA says
> the factor can range from .4 to .7 and I think it
> also said that there is a
> table in the AISI manual regarding this factor.  Can
> anyone fax me this
> table or section from the AISI manual?  Also, the
> section properties and
> member designations are different between AISI and
> SSMA.  If I could get
> someone to fax the explanation for the AISI
> designations, and possibly a
> list of member section properties so I can cross
> check with the SSMA values,
> I would also be very happy.
> 
> Thanks,
> 
> Joe Grill
> 
>  
> 
> Joseph R. Grill, P.E. (Structural)
> 
> Shephard - Wesnitzer, Inc.
> 
> Civil Engineering and Surveying
> 
> 1146 W. Hwy 89A Suite B
> 
> Sedona, AZ  86340
> 
> PHONE (928) 282-1061
> 
> FAX (928) 282-2058
> 
> jgrill(--nospam--at)swiaz.com
> 
>  
> 
>  <http://inet/index.htm> 
> 
>  
> 
> 



		
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