Split Ridge Beams

[MontanaJared]

I have need of a 34' Ridge (2 ply LVL, 11 7/8), which I can get, just no way to transport to my site.

I plan on a 16' section and an 18' section, with the splice joined over a log post. I will nail the plies with proper pattern and plan on using a piece of steel in the shape of a T to bolt the plies together and to the log post. Bearing surface will be the same as post pockets on each side of the log (10" log at the tip, dressed to width of beams).

Rafters will be joined to the side of the beam with connectors and birdsmouths at the plates.

Am I ok at the splice? It will be tricky to get in place, but I think, if the splice is "legal", once I get some rafters in, things will solidify.

Comments?

J

[John Raabe]

As to whether it is legal is a question for the inspector or an engineer. But the basic design is often used in timber construction.

I might suggest cutting a single seat in the top of the beam and setting the mating LVLs together so the bolts and/or screws have a solid purchase. You can also cut a steel "T" with bolt into the beam and post.

[Don_P]

Yes, it is fine, let the supplier know what you want to do and they will engineer accordingly. The continuous beam, 34' long with a post in the middle, from memory the loading reactions are 5/8 of the load on the log post and 3/16 at each end. With 2 simple beams the load is 1/2 on the log post and 1/4 at each end.

[MontanaJared]

Thanks for the tips. You have me curious on the difference in loading between a continuous beam and two separate ones. Wonder why there is a difference...

[Don_P]

The loading for a simple beam is pretty obvious, if the load is uniformly distributed, half the load is carried by the post at each end of the beam. The center post is carrying half the load from 2 beams so the overall reactions on the 3 posts is 1/4 total load at each end and 1/2 total load on the center. That part is pretty intuitive.

Now imagine a continuous beam balanced over the center post. To an extent we can kick out the end posts and it will still take quite a bit of load, the beam is rigid over the center post. That post is taking more of a share of the load under that long continuous beam. The greatest bending moment(s) in that continuous beam also move outboard a bit from the center post. Compare figs 1 and 29 here;
http://awc.org/pdf/codes-standards/publications/design-aids/AWC-DA6-BeamFormulas-0710.pdf

If you want to keep exploring that end of things the AITC (heavy timber/glulam) and AISC (steel) manuals get into long beams, splices and multiple posts. The math has the same basis it just continues on deeper. Their beam formulas may be online. It gets pretty interesting in a mind numbing way