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

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Thanks, Scott.

That is almost verbatim what my "timber expert" told me this morning. He
said the rotation that I tried to illustrate is to be expected. His
conclusion: don't worry; be happy.

Regards,

T. William (Bill) Allen, S.E.
ALLEN DESIGNS
Consulting Structural Engineers

> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu]
> Sent: Monday, April 14, 2008 10:27 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Existing Beam: Repair or O.K.?
> 
> If the sketch is representative of the situation (i.e. a "crack" on one
> side
> with the rotation) and it is a solid timber member, then it is most likely
> a
> check due to tangential shrinkage of the wood (i.e. the rings of the tree
> wanting to shrink in circumference due to loss of moisture/drying).  Such
> things are VERY common in large timber members.  Large timber members will
> almost definitely check due to loss of moisture.  Such timbers usually
> start
> out with moisture contents well above 19% (typically in the high 20's to
> low
> 30's if not higher sometimes) and frequently are put into service with
> moisture contents still well above 19%, unless they are kiln dried.  The
> only difference between a kilned dried timber and a green timber with
> regards to checking is when the checking occurs.  Generally speaking, such
> checks are accounted for in the shear provisions of the NDS and thus are
> generally NOT a concern.  Only where there is REALLY severe checking that
> results in checks that pass through most or all of the cross section is
> there generally concern (i.e. maybe two checks on opposite sides of the
> member that then meet in the middle).  If the check only passes through
> less
> then one half of the member, then it is generally not a concern.  It is
> just
> part of dealing with wood.
> 
> But, if it gives you warm fuzzies to repair or replace, then who am I to
> stop you?
> 
> Now, if this is a glulam or some other engineered wood member, then that
> is
> a whole other ball of wax.
> 
> Regards,
> 
> Scott
> Adrian, MI
> 
> -----Original Message-----
> From: Abolhassan Astaneh-Asl [mailto:astaneh(--nospam--at)ce.berkeley.edu]
> Sent: Monday, April 14, 2008 10:22 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Existing Beam: Repair or O.K.?
> 
> 
> 
> Dear Mr. Allen:  Of your three options below, I think the third option
> might
> be the way to go which to repair the damaged beam. However, we may need to
> find out first what caused this crack in the beam? Without knowing the
> cause
> of damage, the repaired beam can also be cracked for the same reason the
> original beam cracked. Option one "to do nothing" does not seem to me an
> option at all. Pretty much you have two options either repair the damaged
> beam and if that cannot be done in a reliable and economical way, then the
> beam has to be replaced.
> Hope my 2-cents is helpful.
> A. Astaneh-Asl, Ph.D., P.E.
> Professor and Consultant on
> Structural Engineering, Earthquake Engineering and Protection of
> Buildings and Bridges against Blast and Impact
> ==========
> 
> From: "Bill Allen" <T.W.Allen(--nospam--at)cox.net>
> To: "Seaint" <seaint(--nospam--at)seaint.org>
> Subject: Existing Beam: Repair or O.K.?
> 
> 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>=20
> 
> Consulting Structural Engineers
>  V (949) 248-8588 . F(949) 209-2509
> 
> =====================================
> 
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