does girder imply the /short/ dimension?

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    Jorge De La Rosa

    What were the other options? I may be reading this wrong, but it doesn’t sound like girder is correct. Girders support the beams running perpendicular to girders, so girders may be longer, but.......

    sorry, just wanted to give this answer a try...would love to hear what others say

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    Jonathan Chertok (Edited )

    thanks jorge.

    yeah. some of these questions are weird because the tests have a /visual/ reference but no /dimensions/ and it is confusing (at least to me) as to when you can rely on an illustration without dimensions.

    i mean, normally anything without a scale is specifically Not To Scale and i think as a profession we specifically don't interpret non-dimensioned drawings. sorry, i wouldn't try to unpack this issue like this but i see so many people getting confused on non-dimensioned drawings and it reminded me of this one. it is confusing.

    same thing with the north arrow flipping all over the place. it is so contrary to standard practice it is really very confusing.

    so on this - check me here please - girder implies the deep beam which means it is going long ways and the joists/trusses/beams (which rest on the girders) are going short-ways. https://en.wikipedia.org/wiki/Girder

    i think i got it. part of the issue here is just the cognitive dissonance of getting a drawing without dimensions i think. your brain starts to get confused and the term "girder' starts to flop around in your mind because you are not sure what you are looking at. i mean, i'm guessing here but i suppose you can rely on non-dimensioned drawings to the extent that if something LOOKS longer than something else then it is in fact longer and you can just insert some random set of dimensions if it helps you solve it...

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    Jonathan Chertok (Edited )

    wait. is that right? can't you have really deep girders running the short dimension but carrying the heaviest load with longer beams (with much shorter spacing) resting on it...? oh boi...

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    Audrey Voorhies

    Girders go in the short direction. Steel framing should utilize rectangular bay units, with lightly loaded beams spanning farther than more heavily loaded girders. Lateral forces are more critical in the short direction as well.

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    Jonathan Chertok

    hi audrey. thanks.
    i find it very hard to think about these things abstractly and would much rather be presented with a framing plan. dunno. maybe it’s just me.
    so, yeah - lateral forces are most important to watch out for in the short direction (because rheblonger direction has more “depth” like a beam resisting bending moment).
    on the girder - it would be placed in a “bay” in the SHORT dimension. the long dimension would be a beam.
    OK, absent any dimensions you would simply look at a drawing and see that one dimension /looked/ longer so that would be the beam and the girder would be in the short dimension i guess.
    hmmm. still can’t quite muddle through this one. some of these seem like zen koans or something...

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    Audrey Voorhies

    Ah...I see. Just try to think of it in terms of bullet points or lists. When studying I write things down in bullet points so it is clearer.

    Framing Plan: (from light load to most heavy)

    1. decking
    2. joist
    3. beam
    4. girder
    5. column
    6. bearing wall

    Then I might expand on it. Also, look at BCI too for diagrams. Hope this helps!

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    Jonathan Chertok

    thanks for helping me think this through audrey.
    in thinking about it i may just have to draw my own framing plan to make sense of anything without dimensions. it’s one thing to draw a bay but adding the framing may help even more.
    i guess i’m so used to looking at things “concretely” i have a hard time when it is an abstract question with no dimensions. it’s like it is specifically “non-architectural”...

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    Jonathan Chertok

    let me follow up with this.

    if i tell you i am shortening the length of the “bays” does this imply the girders are getting shortened?
    i mean, the term “bay” - does it imply the short distance and thus that the girders are getting shortened??
    i mean, “bay” doesn’t imply anything about which direction are the girders - does it?
    it’s like a word salad without illustrations isn’t it?

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    Anton Gross

    I would typically located the Girders in the short dimension. You would typically prefer all the beams and girders to be the similar depth, so no wasted vertical space for nothing really. So, if the Girder or heavier and stronger member goes in the short dimension, it will be taking half the tributary load from all the beams that are resting on them. That's a LOT larger load and larger tributary area than each beam, so the member will have to be stronger. So, it will run in the shorter dimension, otherwise the incredible load will mandate that the girders get really deep and that is less efficient.

    I hope this helps clarify the situation.

    Also, a bay can be almost any dimension. The term bay does not imply any orientation of direction of any members at all.

     

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