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

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I have seen plenty of examples of such twisting and warping (one example
that comes to mind the end of a cantilever had twisted about 15 to 20
degrees at least).  I will admit that it can be a bit disconcerting (thus,
making it hard to "don't worry; be happy"), but once you go back and
understand what is going on it becomes much less disconcerting.  That is
usually what the letters are for...to make our timber framing clients more
comfortable with something that is perfectly normal (most of the time), even
if it does look disconcerting.

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Bill Allen [mailto:T.W.Allen(--nospam--at)cox.net] 
Sent: Monday, April 14, 2008 4:43 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Existing Beam: Repair or O.K.?


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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