In-place Wood Column - Improve Slenderness
In-place Wood Column - Improve Slenderness
(OP)
I have a nominal 6x6 sawn-wood column with a 14' unbraced length. The column supports an eccentric load from 16' span & 8' beam spans (supporting roof trusses) on opposing sides of the column. The bottom of the column has been cast in concrete - literally; as an interior column for a pole barn application. My calculations for the beam design portion including Le show that Cs is 56.2; which is > 50. So, according to my calculations, I need a minimum of a 7x7 column for the slenderness. Can I construct an 8.5x 8.5 built-up column using 2x's glued and fastened to the sides to improve the slenderness? What type glue is appropriate? Is there any design information on line from one of the wood industry institutes or organizations?
Thanks,
DCEngr1
Thanks,
DCEngr1






RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
You can minimize this slip by using the glue you talked about, but I wouldn't count on it in the calcs, just a belt and suspenders kind of thing.
That being said, I might check it with a pinned base since the composite section will not be present where it is fixed.
Well, let me clarify..... calc the allowable compression stress assuming pinned.
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
I have given some thought to adding some steel to this, but if I can, I would like to stick with wood.
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
Is there any way you can cut down the span? Are you taking the L to the centerline of the trusses or to the bottom face?
Try to justify a smaller L if possible.
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
Personally, I would just use a glulam column and be done with the mess.
Mike McCann
MMC Engineering
RE: In-place Wood Column - Improve Slenderness
RE: In-place Wood Column - Improve Slenderness
a) adjacent nails are driven from opposite sides of the column
b) all nails penetrate at least 3/4 of the thickness of the last lamination
c) 15D<=end distance <= 18D
d) 20 <= spacing between adjacent nails in a row <= 6tmin
e) 10D <= spacing between rows of nails <= 20D
f) 5D <= edge distance <= 20D
g) 2 or more longitudinal rows of nails are provieded when d> 3tmin
15.3.4 (for bolted built-up columns)
a) a metal plate or washer is provided between the wood and the bolt head, and between the wood and nut
b) nuts are tightened to insure that faces of adjacent laminations are in contact
c) for softwodds: 7D <= end distance <= 8.4D
d) 4D <= spacing between adjacent bolts in a ros <= 6tmin
e) 1.5D <= spacing between rows of bolts <= 10D
f) 1.5D <= edge distance <= 10D
g) 2 or more longitudinal rows of bolts rae provided when d > 3tmin
D = diameter of fastener
d = depth (face width) of individual lamination
tmin= thickness of thinnest lamination
I hope that helps. I would also make sure the additional plies are the same species and grade as the core.
RE: In-place Wood Column - Improve Slenderness