built up wood tension members
built up wood tension members
(OP)
How would you calculate the net effective section area of a 2 or 3 ply built-up timber strut for tension resistance e.g. Boundary beams in roof diaphragms? Thanks a bunch
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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built up wood tension members
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RE: built up wood tension members
RE: built up wood tension members
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RE: built up wood tension members
Are you saying that if we build a 2-ply long built-up tension member by half lapping 16 ft. lengths (8’) of 2 x 6 that the useful section for tension would be 3” x 5 ½”. I feel it would be true of a section for compression (axial load), but it seems counterintuitive for tension??
BTW the fasteners I would visualize as bolts or spikes from ply to ply
RE: built up wood tension members
I don't think that is what tlhs is saying. The terminology is very loose, (" 2 or 3 ply built-up timber strut" & "2-ply long built-up tension member by half lapping 16 ft. lengths (8’) of 2 x 6 "), admits more than one interpretation, and the interpretation I would guess for you second post leaves an available cross section of a single 2x6 less the proper allowance for fasteners as queried by focuseng.
I'd suggest you draw a sketch of what you're thinking, and I'm sure you'll obtain a crystal clear and correct response within hours.
Good luck!
RE: built up wood tension members
J
RE: built up wood tension members
What I believe was your intuition in your previous post is correct. You get, at absolute maximum, the tension value of a single 2x8 in this case, knots and all. Your system's tension value will depend upon the fasteners used and their locations as well as the wood quality. I generally prefer nails which part the wood grain in these connections, others will prefer bolts which actually remove wood material. Your engineer will look for the "weakest link", which maybe the single 2x8, or the effective net section with bolt hole material removed which depends on locations of bolts, or the fasteners themselves and their various modes of failure. The code gives explicit guidance on fastener locations and calculations.
RE: built up wood tension members
BA
RE: built up wood tension members
If you get wood cheap, or labor and skill is expensive, that's okay.
If you were building a boat, you'd probably use a scarf joint and a good adhesive to develop the full cross section of the wood, but that is a little skill-intensive.
Mike Halloran
Pembroke Pines, FL, USA