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RE: R-Factors Coldform hat sections

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I see what you're suggesting.

We have spreadsheets with the AS4600 formulae coded, and can do the analysis
with various restraint levels.

My dilemma is the degree of torsional restraint that can be legitamately
assumed, so as to run it in this manner.

The only other way I can think of is to run Ben Schafer's CUFSM which I
believe can model a torsional restraint attached to one flange only?

AS4600 does allow for members or sections not explicitly covered by the
published equations to be verified by testing.  One of our major players
"Stramit" have done this according to their documentation
http://www.stramit.com.au/products/structural/tophats/tophats.html, but
there are a number of other's that are just "winging it".

Thanks for the links, look forward to browsing them.


Roy Harrison
 
Roy Harrison & Associates
Consulting Structural Engineers
Adelaide - South Australia
 
mailto:ro35984(--nospam--at)bigpond.net.au
http://users.senet.com.au/~tectonic/

	-----Original Message-----
	

 


-----Original Message-----
From: Paul Ransom [mailto:ad026(--nospam--at)hwcn.org] 
Sent: Monday, 10 April 2006 1:38 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: R-Factors Coldform hat sections


> From: "Roy Harrison" <ro35984(--nospam--at)bigpond.net.au>

> How would you allow for the torsional restraint provided by the 
> sheeting attached to the tension face, in a rigorous analysis using 
> Excel?

Use the analysis calcs from the standard for continuous lateral bracing with
approriate torsional bracing - you could use Excel to perform this analysis.
That's what CFS is doing. Then test to ensure that your assumptions are
valid.

> The Australian code AS4600 "Cold-formed Steel Structures" is based on 
> = the extensive work that has gone into the development of the AISI 
> LRFD Specification. =20

> On the other hand there are a number of manufacturers supplying a 
> similar product with published selection tables, purportedly based on 
> AS4600.

Does the AS4600 require confirmation testing outside the explicit
limitations of the defined application of the R-factor? If so, the
manufacturer must have done this to be in compliance with the standard. I am
aware of manufacturers here who provide similar tables or supply system
components with no compliance testing. The product may still be adequate,
but statements of compliance are stretching professional ethical limits. 

> In view of the number of years this form of member has been in the 
> marketplace, both here and overseas, I am trying to track down any 
> non-proprietary research data that has been published.

Try contacting:

Canadian Sheet Steel Building Institute
www.cssbi.ca

The University of Waterloo Cold Formed Steel Research Group
http://www.civil.uwaterloo.ca/CCFSRG/Default.htm
 
Centre for Cold-Formed Steel Structures at University of Missouri-Rolla
http://campus.umr.edu/ccfss/

Thin Walled Structures Research Group - Johns-Hopkins University
http://www.ce.jhu.edu/bschafer/

The Structural Stability Research Council does not concentrate on cold
formed steel but has some published proceedings that may cover your topic.
http://campus.umr.edu/ssrc/

Of course, the AISI may be able to provide some guidance as well.
http://www.steel.org/

-- 
R. Paul Ransom, P. Eng.
Civil/Structural/Project/International
Burlington, Ontario, Canada
<mailto:ado26(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>

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