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Re: Reattaching a subpurlin to a diaphragm

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Bill,
 
Did you have a chance to look at the purlins and plywood (from below) at the location of the failed sub-purlin?
There is no point in trying to adequately attach the new sub-purlin to the deteriorated diaphragm.
 
V. Steve Gordin, SE
Irvine CA
----- Original Message -----
From: Bill Allen
Sent: Friday, July 10, 2009 10:40
Subject: RE: Reattaching a subpurlin to a diaphragm

I think that would be fine if the sub purlin was not located at a panel edge. If it is located at a panel edge, then the sub purlin is used to transfer the diaphragm shear from sheet to sheet.

 

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 ? F(949) 209-2509

-----Original Message-----
From: Ralph Kratz [mailto:rhkratzse(--nospam--at)aol.com]
Sent: Friday, July 10, 2009 10:31 AM
To: <seaint(--nospam--at)seaint.org>
Cc: Seaint
Subject: Re: Reattaching a subpurlin to a diaphragm

 

Does the subpurlin "figure" without composite action with the sheathing?  If it does, would gluing (purely for lateral restraint) be adequate for a single purlin repair?

 

Ralph 

Sent from my iPhone 3G


On Jul 10, 2009, at 10:19 AM, "Bill Allen" <t.w.allen(--nospam--at)cox.net> wrote:

I am looking at some roof repairs (yeah, I've finally made the "Big Time") at a commercial structure. It is a typical panelized roof with 2X4 sub purlins spaced at 24" spanning 8'-0". These sub purlins are attached to the purlins with FN hangers. Somewhere along the line, moisture got between the roofing membrane and the insulation foil which allowed corrosion to attack the FN hangers. Recently, one sub-purlin failed. Fortunately, no one was in the space at the time.

 

The question I have is regarding the attachment of the replacement sub purlin to the existing roof diaphragm. Of course, the owner would rather not remove the existing roofing to re-nail from above. However, considering that the diaphragm is probably only 1/2" thick, I really don't see any other way. Some of the sub purlins are attached at the panel edge some are not but the only way to know that is to remove the roofing.

 

Does anyone have any ideas?

 

TIA,

 

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 ? F(949) 209-2509

 

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