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Wood: a built-up header
A 2x12 header over a 12 ft opening: two plies fail in bending, three plies pass, and the nailing between them governs.
Transcript
Wood: a built-up header.
Start
Wood types are under the Wood tab of the wizard. Pick the sawn lumber beam.
The inputs
Here is a built-up header over a 12 foot opening. Douglas Fir-Larch, number 2, two plies of 2x12, nailed together. The dead load is 150 and the live load 300 pounds per foot.
Two plies
Two plies are not adequate. Bending is 2,286 pounds per square inch, against 1,788. That is a ratio of 1.279, and everything else passes.
Three plies
Change the plies to three, and the header is adequate. The largest reaction is 4,049 pounds.
The check that governs
Bending is no longer what governs. It is now the fastening between the plies, 440 pounds per foot against 486, a ratio of 0.906. A third ply adds a joint, which is why the nailing check is there, and why you should open it.
The reference values
A plain word on the reference values. The NDS 2024 Supplement is not on file, so the wood tables here are 2018 values, marked for review. Enter your own if yours differ.
Report and sheet
Then print the report, with every check, its equations and its clauses. Print the drawing sheet on your own title block, at the size you choose. Or export the same sheet as a DXF for your CAD software.
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