Glulam Beam (less than 12" deep) allowable stress
Glulam Beam (less than 12" deep) allowable stress
(OP)
Normally, we specify 24F-V4 for ss beams and 24F-V8 for cantilever/continuous.
Lately, I have been getting some feedback that "column-rated" Glulams have been installed as beams (we had calculated various 3-1/8" x 9" deep and 5-1/8" x 9" deep beams, to fit within 2x10 floor joists). The builder claims that all Glulam less than 12" deep is available only as "column-rated" laminations, and therefore it was our "error".
Has this been noted by anyone? The combination symbol may be as low as 16F for the under 12" deep glulams.
Lately, I have been getting some feedback that "column-rated" Glulams have been installed as beams (we had calculated various 3-1/8" x 9" deep and 5-1/8" x 9" deep beams, to fit within 2x10 floor joists). The builder claims that all Glulam less than 12" deep is available only as "column-rated" laminations, and therefore it was our "error".
Has this been noted by anyone? The combination symbol may be as low as 16F for the under 12" deep glulams.





RE: Glulam Beam (less than 12" deep) allowable stress
RE: Glulam Beam (less than 12" deep) allowable stress
What may have happened is that the contractor's supplier didn't stock 9" material so he ripped down deeper stock. If you took a 5 1/8 x 18 Douglas Fir glulam and cut two 9" nominal pieces out of it you would no longer have an allowable bending stress of 2400 psi.
The center of the 18" glulam would be made up of L3 laminations. It would be safe to use the design values for Douglas Fir combination #1 which is glued up using all L3 laminations.
Richard's Rule: It is always available but not at the price the contractor wishes to pay.
RE: Glulam Beam (less than 12" deep) allowable stress
Sounds like that's what happened. Thanks!