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Re: Existing Beam: Repair or O.K.?

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If the beam is as large as you've noted, and spans only 12.5 feet, I would think the reduced section should be able to carry the expected loading.  Unless the building is being reroofed at the same time floors 2 and 3 are holding 8 hour ASCE seminars, a much smaller beam should check for shear and bending.  shear does sound like the culprit.  However, it appears to be a radial split for a timber of such large dimension. 
All that aside, if numbers don't check, or to appease the inspector, i'd go steel flitch plate, each side, and fill the split with an epoxy.

 
On Mon, Apr 14, 2008 at 10:18 AM, Gerard Madden, SE <gmse4603(--nospam--at)gmail.com> wrote:
If it's a timber and those dimensions, it definitely sounds like a check.

-gm


On Mon, Apr 14, 2008 at 4:41 AM, Gary L. Hodgson and Assoc. <ghodgson(--nospam--at)bellnet.ca> wrote:
Bill
I had a similar problem about 3 years ago with a smaller beam. I got an engineer who does nothing but wood/timber design and he advised me that it is a check(if I remember correctly) not a crack. A crack goes all the way through whereas a check is only partially through. At 69, I am still learning. Any way he said not to do anything about it, as it has been there for 60-70 years. Rather than suggest that solution to you, I would determine its age, etc and talk to a wood expert. I wish you the best of luck with it.

Bill Allen wrote:

I'm working on a small commercial remodel in Southern California. The part of the work for which I'm responsible is nearly complete. However, when the inspector came out to finalize the framing, he noticed problems in an existing beam which is not part of my original scope of work. The building is three stories and is rectangular. There is a beam line running down the middle of the long direction. For my work, I had to remove and replace the existing beam where the office is being remodeled. Beyond my work, the existing beam is unmodified. What caught the inspector's eye are small holes drilled in the beam used to pass electrical conduit. I haven't run the numbers yet, but I believe these holes are O.K. What is troubling is that, on one span, there is a long crack down the wide face of the beam for most of the length. Worse yet, it appears that the beam above the crack has rotated slightly. Below is a sketch prepared by my original CAD program. I've exaggerated the rotation, but it is obvious. The beam is huge. It's 18-3/4"x701/4". It spans about 12-1/2 feet and supports two floors and a roof. I'm concerned about two things; the ability of the beam to transfer VQ/I stresses through the cracked region and the ability of the beam to remain stable if the crack propagates. Maybe there are other things I should worry about. There are three methods of addressing this problem that I can think about off the top of my head and they are:

1. Do nothing; the beam is still structurally viable.

2. Add Simpson LTP4s at 12" o.c. or so which would stitch the crack in the hopes that it will keep the crack from enlarging/propagating and will hopefully transfer the VQ/I stresses by an unknown load transfer path.

3. Don't mess around with it and repair the beam by sandwiching two PSLs, one on each side and designed to take 100% of the load. I would have the contractor jack the beam as far as he can (there are bearing walls above) before he bolted these beams to the existing beam. If I could get 100% of the load off the existing beam, it would then act to only transfer the load to the PSLs.

What would you do and why?

TIA,

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

ALLEN DESIGNS <http://www.AllenDesigns.com>


Consulting Structural Engineers
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-gm



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David Topete, SE