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RE: Diaphragm

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Gary:
I will look to another metal deck and discuss the matter with clients.
Regards
Ashraf

-----Original Message-----
From: Drew Morris [mailto:dmorris(--nospam--at)bbfm.com] 
Sent: Tuesday, May 30, 2006 8:15 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Diaphragm

As mentioned previously, you could use another metal deck under the 
standing seam roof.   20 ga 3" N deck (joistsa @ 10' oc) as a single 
span has an allowable load of 65 psf.

Ashraf, Mohammed (Qatar) wrote:

>Gary:
>I looked to Bemo Manual and they also say 5 feet spacing. So I will try
>to reduce spacing of joists and keep it within limits as you mentioned.
>But how can I defend it to the client since it has large cost
>implications?. How about providing purlins at a spacing of 5' and
>keeping joists at a spacing of 10'. Does it help to keep joist spacing
>at 10'?.
>The minimum design load is 25 psf. 
>Thanks for your help and regards
>Ashraf
>
>-----Original Message-----
>From: Gary L. Hodgson and Assoc. [mailto:ghodgson(--nospam--at)bellnet.ca] 
>Sent: Tuesday, May 30, 2006 3:05 PM
>To: seaint(--nospam--at)seaint.org
>Subject: Re: Diaphragm
>
>Ashraf,
>I had the same feelings as Daryl when I saw a spacing of 10 ft between 
>joists. Of course, we are used to snow loads,
>(here in Niagara Falls 39 psf on a flat roof), but I would think you 
>should be designing for a minimum of 20 psf (that
>is code here in Ontario).  This probably covers construction loads, 
>etc.  My Butler Manual recommends a spacing of
>5 ft for their MR24 standing seam roof, but they don't say why or what 
>are the ramifications of larger spacings.  I have
>walked on a ss roof with 5'-6" spacing and it was like walking on mush.
>
>The contractor told me to stay over the purlins.
>       In your case, the flat bar bracing depends on local conditions 
>and abilities of the work forces.  Bridging is not bracing;
>rather it is individual bracing of the joists to stabilize them during 
>construction, as individual joists have a tendency to roll over easily.
>
>The Can. Institute of Steel Const emphasizes that bridging is not
>bracing.
>Gary
>
>
>  
>
>  
>



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