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RE: Boring through GLBs

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It's hard to believe a contractor would do that without asking, but it I have seen it before. www.apawood.org has a publication for holes in glu lam beams, pretty much the standard prescriptive limitations. I wonder if the manufacturer would write a letter, but if they would, seems that would be to your benefit.
 
Jeff


From: Donald Bruckman [mailto:bruckmandesign(--nospam--at)verizon.net]
Sent: Saturday, December 08, 2007 9:05 AM
To: seaint(--nospam--at)seaint.org
Subject: Boring through GLBs

I have a building I designed being constructed here in SoCal which has a clear-spanned GLB floor girder system about 35 feet long with 36? deep beams.  A few weeks ago I got a call from the GC telling me that the electrician, for reasons known only to the electrician, drilled a single 1 ¼? diameter hole through the GLB to fish some conduit through to an elevator room.  After quizzing the GC about where the holes were, I found that they were bored about 10 feet from the point of support and near the center of the depth of the beam. 

 

I was a bit miffed that it happened, but figured a hole that small in the center 1/3 of the depth of the beam away from the area of max moment wasn?t going to be a big deal. 

 

Well, my engineer was extremely upset about it and threatened to make them replace the beam. He finally agreed to approve it but I could not get any impression out of him whether it really was a big deal structurally or if he was just putting on a show to teach the GC a well deserved lesson.  Meanwhile, the building inspector gets into the act and is asking for a letter from the manufacturer approving the holes, an idea I found very odd.

 

My question:   What?s going on here?  What do I not know, after all these years in the biz, about holes in GLBs?  From a reduced section standpoint, away from the point of max moment and near the center of depth, such a small hole seems relatively unimportant to me. Am I missing something?

 

-DB