Shear Deflection – Prefab Wood I-Joist Example Calc (c) Jeff R. Filler, Pell City, 2022 Continuing our discussion on shear deflection of wood beams (joists, etc.), let’s look at a prefabricated wood I-joists. Basic design information for prefabricated wood I-joists …
In the example above (link) we calculated a deflection of 0.599 in. How accurate is this number? (I showed it to three significant figures … accurate to half a percent?) Leaving out, for now, the accuracy/precision of the other input, …
E app (`Eee app’, `Eee apparent’, Apparent Modulus of Elasticity) is a design property for wood construction. It comes from the Modulus of Elasticity of the wood (E, MOE, Young’s Modulus). It’s not a `true’, or `pure’ property, and it …
As an engineer I tend to design structures from the top down. First the roof loads, which determine rafters, or trusses, or whatever roof framing members. Then the beams/headers/girders supporting the rafters, then the columns or walls supporting the headers, …
Jeff R. Filler, (c) 2021 The dead weight deflection of a beam, rafter, etc. is the amount the beam deflects, bends, sags, due to the `dead weight’ of the things it is carrying, including itself. Going back to the example …
… now for `deflection’ … So far we’ve been dodging the `deflection’ issue. `Deflection’ of a beam, rafter, girder, header … is how much the beam `bows’, or bends. For a beam or rafter supported at it’s ends, the deflection …
Okay, now let’s do a (free, online) check of the concentrated load situation. Note that I am looking at the concentrated load separately from the uniform 20 psf live load … yeah!, the two loads are not taken to act …
Designing a roof rafter … (bending stress) … Linda wants a barn-shelter for her goats. Okay – I’ll do it. `Twelve by twenty-four.’ `Let’s go walk the site. It’s got some slope. I’ll make a stepped-barn, each section will be …
Miles asked me to design a truss for his shop. I grabbed my clipboard. Wood? Yes. Rough sawn? Yes. Rise/Run? 4/12. Width? 21 feet. (Hmmm … I am sketching as we go along.) Oh, 20. You mean 20 to center? …