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RE: Sawn Beam Repair?

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-----Original Message-----
From:	Bill Allen [SMTP:BAllenSE]
Sent:	Wednesday, October 01, 1997 8:13 AM
To:	'seaoc(--nospam--at)'
Subject:	Sawn Beam Repair?

I am working on a project that is currently in construction. 
This is a single family residence. I have specified a 4x12 #2DF 
beam supporting some ceiling framing at the second floor. 
According to the contractor, the beam had a slight crown (upward 
camber) when installed. Near the midspan of the beam, there 
exists a knot near the bottom edge of the beam near the midspan. 
A crack has developed at the knot and the beam is sagging.

Short of replacing the beam, is anyone aware of a practical 
technique to repair this beam?

Bill Allen

Bill, being a 4x12, the loads can not be that bad.
1.You might try plating (strapping) the lower half of the beam 
designed for the tension capacity of the member at maximum 
bending. Considering the location of the knot, it would not be 
difficult to determine end distances to center of bolt. If the 
capacity is small enough for nailing of straps then you don't 
have much problem. Just use a heavy enough gauge of strap to 
avoid elongation in the strap.
2. You can also try to "Flitch" plate the beam, but this is more 
difficult since it requires slicing up through the center of the 
beam to slip a plate it. This may be desirable if the beam is to 
be exposed.
3. You can also try to sandwich 2x12's to each side of the beam 
and 'sister' them together (similar to a micro-lam splice) to 
support the load in the failing beam.

There are a bunch of ways to deal with a beam such as this that 
does not carry too much load. How did this beam get in 
originally. I would assume you specified a #1 grade or better. I 
don't think that a number 1 grade beam is allowed to have a know 
located mid-span at either edge (tension or compression)?

Dennis Wish PE