Evaluating splits and checks in sawn timbers

[AJGIII]

What references to use, and how does one go about determining if checks in timbers are "substantial" as alluded in the Timber Design Manual.

The situation I've seen recently is a nominal 8x14, 16 foot long residential garage door header with splits on one side about 2 1/2 deep. Can't see opposite side. Splitting is along center, fairly consistently from end to end. Ends are not visible. Second floor wall is directly above, deflection is not excessive measureed under the beam, but upstairs, floor slope and offset of window openings of the wall above the garage door header do slope to the center of the beam. Floor slope ranges between 1 1/2 to 2 1/2 percent at outside walls which are 4 feet outside beam ends. Slope reduces at center (typical). No major cracking in drywall--only very minor. But all of the second floor conditions could be superflous to my Q. I figured it might be interesting. thanks.

 

[boo1]

A check is a separation of the wood along the fiber direction. They are probably causes by drying stresses. All timber larger than a 6 x 6 will form a crack on at least one face.

If they are at the nuetral axis they do not effect the delection and bending load capacity.

 

[boo1]

i did not answer your other queation, refer too:
1.AITC Technical Note 18

2.BOCA Report 96-6 & SBCCI Report 9625A:
Horizontal Shear Stress, Fv, shall be modified by Shear Factor, CH;
0.69<=CH=KLx[850/(b x L)]0.2<=1.0
where:
KL=loading coefficient (1.0 for uniformly distributed),
b=width of beam, in.,
L=span of beam, in.,

3.APA has an article Evaluation of Check Size in Glued Laminated Timber Beams:

http://www.apawood.org/pdfs/managed/EWS-R465E.pdf

 

[AJGIII]

Thanks, and understood.

When splits/checks pass through centerline of the beam, eg, over 1/2 its width, the beam begins to behave like two stacked beams, and performance is degraded, so that is one parameter. I like to have source docs in what I do since there is always someone who wants to challenge. In this instance, I told the owner the condition was not a prob., but he's convinced he needs repair.

 

[AJGIII]

Ahh, excellent. I'm in (former) ICBO land, but will search out the SBCCI and BOCA refs. I tried theother day, and then again today, and couldn't get teh APA pdf to open or download. May have to buy it. :-( Ha!

Thanks again, v/r
John