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RE: Detail Review

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Actually I mentioned an L/480 and I also believe the rotation would be about the neutral axis which would make the movement half of what you indicate.  That aside, I come from “ranching folk” in Eastern Montana and they have an _expression_ “picking the fly s___ out of the pepper”.  I think quibbling over a couple of hundredths of an inch (in this instance) is ridiculous as I have never seen a joist cut and installed to that tight of a tolerance anyway.  I believe as others have stated that what the joist is hanging from, and construction sequence is more of an issue.

Joe Grill

 

-----Original Message-----
From: S. Gordin [mailto:scgordin(--nospam--at)hotmail.com]
Sent: Thursday, August 05, 2004 4:31 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Detail Review

 

Joe,

 

For L/360 deflection limit, rotation of a 12" joist amounts to 0.11". 

That appears to be a lot.  If not for the floor above, consider at least the compressive - continuous and quite unsightly - distortions of the ceiling joint below. 

 

Steve Gordin

   

 

 

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

From: Joe Grill

Sent: Thursday, August 05, 2004 4:05 PM

Subject: RE: Detail Review

 

I just did a quick calc. and if you have a 15’ span joist limited to l/480 deflection the horizontal dimension translated at the support (for a 11 7/8” joist) is 5/100ths inch +/-.  Doesn’t seem like that is a big problem.  Mikes comment about cross grain tension is worthy of consideration, although it is a PSL.  Would be a good question for Trus-Joist.

 

Joe Grill

 

-----Original Message-----
From: S. Gordin [mailto:scgordin(--nospam--at)hotmail.com]
Sent: Thursday, August 05, 2004 3:38 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Detail Review

 

Bill,

 

IMO, joist rotation and gypboard crushing may be a problem.  At a certain point, rotation may distort the floor above.

You may want to talk to SST people - they are pretty good about answers to non-standard situations.  

Besides, if you are going to fire-protect the joists anyway, won't it be better to throw 2x ledgers on both sides?     

 

SG 


>>> T.W.Allen(--nospam--at)cox.net 08/05/04 02:28PM >>>
Dear Colleagues;

 

My client has asked me to review a proposed detail. I have my opinions, but,
being one with an open mind, I would like to get opinions from others.

 

The detail is here:
http://www.AllenDesigns.com/projects/20401/20401_sk03.jpg