retug October 03, 2022

One Way Load Distribution In ETABs

I have used ETABs one way load distribution button for a long time and it works great on flat floors and "slightly sloped roof" to distribute load based on tributary area.

Today though, a coworker of mine noticed on a slightly more pitched roof, angle of about 30 degrees, the one way loading was not working as intended (could not see applied loading due to tributary area).

I built a test model to explore the odd behavior.

Slab section properties uses one way distribution:

(3) sample floors are made, each with the same load and beam restraint layout, but you can see, once the floor becomes "too sloped", the load distribution switches from a line load on the frame elements to merely point loads applied at the edge of the membrane

 

The magic slope where this seems to occur is about 20 degress from horizontal.

Hopefully this post saves someone in the future the pains of troubleshooting this odd behavior

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  • Latest Comments
  • retug on Diaphragm Slicer New and Improved -

    Thanks Trenno.

    I will work to get metric units incorporated, that's a great idea.

    On your second point, I think something like that could be done, it's just a bit awkward with how CSI currently has it setup. In order to make section cuts, I need to unlock the model, ...

  • Trenno on Diaphragm Slicer New and Improved -

    Awesome work S&T!

    Firstly, I'd recommend if you're going to feature the tool on CSI's website then maybe incorporate metric units (aka real units!) 

    Secondly, I'm wondering if there would be a way to set up the workflow using something akin to RAM Concept design strips. Perhaps the strip width ...

  • e95kwon on Transfer Diaphragm Design -

    My understanding is that for a 5-story building you would have:

    • (1) load case A (ELF)
    • (1) load case B for each level except the roof so total (4)
    • therefore (4) load combos for diaphragm design

    I believe the intent is to envelope higher mode actions as you mentioned ...