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Replace built-up wood beam

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Gary,
 
I like Bill Cain's idea for deriving a warm feeling from the beam.  Take it out and build a fire.  Replace the old beam with a new one and tell the designer to quit trying to invent new materials.  Glue laminated beams are made from flat-planed, straight members clamped together on a set-up table under ideal conditions.
 
They could sister new LVL beams onto the sides, not with glue but with through bolts.  It wouldn't be as pretty but it would pass sound engineering judgment.
 
Any reinforcement of the old beam requires shoring up to remove the existing dead loads out of the old beam before attaching the additional elements, otherwise the new elements only take a proportion of the new dead loads and live loads that occur after adding the new elements.  The proportion of loads to the new element is proportional to its stiffness (EI) compared to the combined beam.
 
Post-tensioning could work here if the beam is exposed, but it would require a king post down below the existing beam at the center and tie rods on both sides.  This may not be good for head room below the beam.
 
A new steel beam is the simplest solution, providing more capacity with less depth.  They could always cover it with a wood veneer.
 
Dave Gaines
Pasadena, CA
----- Original Message -----
Sent: Monday, June 05, 2006 5:46 AM
Subject: Re: built-up wood beam

List,

I have been asked to review drawings for a house addition,  The designer
has called for an existing beam (9h x 11.25v actual or nominal?) to be
reinforced with a 2" x 11.5" hardwood plank glued on the flat to the
bottom of the existing beam with an epoxy glue.  I am assuming the
original beam is S-P-F or Doug Fir as that is pretty standard around
here.  No grades or species were given. I have never heard of such a
thing and do not want to comment on it if it is acceptable practise but
it seems strange to me.  The house is approximately 20 years old.  I'm
just wanting to feel warm and fuzzy about this.

TIA,

Gary





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