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RE: Side notches in Glulam[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Side notches in Glulam
- From: "Scott Maxwell" <smaxwell(--nospam--at)umich.edu>
- Date: Tue, 18 Aug 2009 01:57:56 -0400
Because some long ridge beams with low loads (i.e. low roof loads) still end up with high enough moments that a solid sawn timber cannot achieve the needed flexural stresses due to lower allowable stresses (even with Select Structural) and due to small available cross-sections (you can get glulams with WAY bigger cross-sections than timbers...timbers tend to max at around 17" or so deep typically).
And from what I can tell, the original design still had a glulam for the ridge beam...I believe they just want to change the connections.
From: Francis Hsi [mailto:hchfrank(--nospam--at)hotmail.com]
Sent: Monday, August 17, 2009 11:39 PM
Subject: RE: Side notches in Glulam
I wonder why would someone use glulam for a small residence with low forces, it doesn't make sense.
I think the client could save more by not using glulam than skim on the connections. Besides why should someone put himself at risk and go against the original design just because the TF wants to save on expansive connectors. By so doing we are digging our own graves.
Subject: Re: Side notches in Glulam
Date: Mon, 17 Aug 2009 16:27:11 -0400
I am not directly aware of any restrictions. "We" have done this on occasion, but we do not have too many situations where we use glulams in timber frame...at least not where we use timber framing joinery. There could be some limitations in the AITC documents. I would have to check.
I would not likely worry too much about changes in the laminations grades...you are removing just a sliver of of material. If you are relying on bearing to take the load, then I might worrying about where the bearing surface is relative to a lamination plane.
In general, I would likely say treat it as a regular timber...thus, you could use the TFEC 1-07 Standard and other typical timber framing stuff. But, verify if there are any restrictions in AITC docs.
On Mon, 17 Aug 2009 16:12:21 -0400, "Jordan Truesdell, PE" <seaint2(--nospam--at)truesdellengineering.com> wrote:
It's a rafter to ridge beam in this case. The original design (stock plans) show lam-to-lam with Simpson hidden hardware. Since the TF has all the shop gear to make the notches, they want to skip the hidden (expensive) connectors and house the joist with GRKs to pin the rafter to the beam. This is a small residence, so the forces are fairly low. All I could come up with is separation of the laminations from bearing stress and possible "changing" of the grade of the top ply if a notch results in an imperfection closer to the edge than allowed (not sure which / if any lumber grades this would apply to). That last part might not even matter if they're balanced since the notch would be in the compression plies.
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