Feb 19, 2022UPD Feb 19, 2022
I've put out quite a few wooden-structure calculations over the years, and very occasionally I'm asked to submit an effective slenderness-ratio check. As long as the spacing between horizontal members doesn't exceed 4.5 m, a 105 mm square column is fine — but the request seems to be "show that explicitly."
Recently, though, there are also requests to raise the horizontal diaphragm of the small roof like a boat bottom to eliminate horizontal beams. That can push the column supporting the ridge past 4.5 m — and the slenderness ratio starts to actually matter.
On the other hand, story height is constrained by load-bearing wall width, so that has to be checked too. Or rather, that's almost always what determines things.
It's fine if you're doing it knowingly — but when you do something unusual, you have to be careful.
P.S. The phrase "minimum second-moment radius" (最小二次率半径) appears in the legal text — I've never heard of it and suspect a typo, but the truth I don't know.
