2012年4月3日 · Note that while this is a good resource, it won't tell you when the beam will actually break. Try replacing 375 lbs total with 90000 lbs/ft.

Shear strain in a long beam is negligible. The shorter the beam, the more it matters. When we're talking about bending strength, we're talking about a beam where half of the fibres are in tension and the other half in compression. In no location does shear strain make any real difference. To me this sounds like something that bending suggests.

2014年4月21日 · If you lay a 2x4 down, the cross-sectiontal area is the length of the beam, L, times the thickness of the beam. That's just 1.5" for dimensional lumber. Stand the 2x4 up, and its cross sectional area is L times the width of the beam. …

2022年6月29日 · Relatively speaking, the strength of a solid rectangular section, such as a 2x4, is width time the square of the depth. So a 2x4 on edge is 2.33 times as strong as one laid flat (1.5*3.5^2 vs. 3.5*1.5^2). The ratio remains the same for 2 of them, unless the ones laid flat are rigidly connected together, so that they act as one piece.

2010年8月11日 · The garage is 10' wide and I'd like to make the shelf 2' out from the wall. I will put a 2x4 ledger on three sides. The fourth side (running from wall to wall), will have joist hangers holding up a 2x4. Then I was going to connect the two 10' long 2x4's with studs every two feet. Then sheet it with 3/4" plywood.

2016年11月22日 · Bending strength is proportional to that value. I have done that math for you: a flat 2x4 has about 20% the strength as a standing one; a flat 2x6 has about 7% the strength as a standing one; a flat 2x8 has about 4% the strength as a standing one; You can see that especially for the deeper joists you lose practically all of the strength.

2018年4月14日 · For a 2x4 oriented edgewise S=1.5x3.5x3.5/6=3.0625 inches cubed; oriented flat, S=3.5x1.5x1.5/6=1.31 inches cubed. Shear strength is about the same in either orientation. Stiffness is similar, but it's width x height cubed /12. That's why a 2x6 is nearly 4 times stiffer than a 2x4, spanning the same distance.

2019年10月8日 · The 2x4's are also the problem. You want to support this from casters only on the corners. That means you need an 8 foot span, as well as a 4 foot cross-span, and you need to keep all this rigid so it doesn't spread and lose strength. Half …

2015年10月13日 · @ LRU I think you’ve calculated the load at which point the beam will “yield” or “fail” in bending. You need to factor a “safety factor” into your calculations. I use working stress, not ultimate strength. Usually shear governs for short …

2019年3月9日 · Hmm, I didn't put the two threads together. In the other thread I think I did explain that we use a full 2x10 for what would be the door jam, that would add much to the strength,, you also want to look at the height I guess of you are right up close to the roof that would be better than if it was dropped 2 feet.