Beam results do not include TOTAL deflection

I am here to raise this bit of a red flag comment that I think is very important and I suspect many users don’t realize. Or they know/knew, but tend to forget in the heat of the moment, like me.

That item is that the beam calc module does NOT present a total deflection result! I raised this question a long time ago and vaguely recall that the response was that the IRC does not concern itself with total deflection, only live load deflection ratios, and therefore that is all that ClearCalcs was going to show.

Fast forward to today when I again realize this omission, and think back to how many beams I designed this year alone, where I considered incomplete deflection results.

So I am here to plead again that ClearCalcs add total deflection to its calculation results. This is critical information that engineers need to know when designing beam sections. And not only is it critical information, but I’ll bet that many users don’t realize that the “Critical Deflection” result does not include dead load. I know it, and yet I still forget.

In my current case for example, I have a simple C8x11.5 carrying 2ft of trib width. The Critical Deflection is 0.447". Fine, less than 1/2", not bad. But then I realize that number is only live load and that total deflection is 0.679" (I had to run a hand calc) and now I am going to upsize the beam. And I have another 15 or so beams in this house I already checked, but now have to upsize because I wasn’t thinking clearly about the true deflection value.

The “fix”, if anyone needs it, is to include the dead load in with the live load value, or in with the snow load if it is subject to a snow load condition governing. And also add in a line load equal to self-weight of the beam. But the real fix is for the result on the screen to include a total deflection value.

Thanks for listening. I have to go back and redesign a bunch of beams.

Hey @WilsonEngineers

Thanks for posting this and sorry about the frustration! First what I think is a more permanent fix for you: we do include an option to consider Dead load + (Live or Snow load) in Project Defaults. I think that should cover what you’re looking to do?

Bigger picture, this is something we’ve been looking to improve but to be honest, we’ve faced a fair bit of challenges / ambiguities on this. One of the main issues we’ve faced is how we define “Total Load”. Here are some examples we’ve been given in the past:

  • D + L
  • D + (L or Lr or S)
  • D + L + Lr + S
  • D + 0.75D + 0.75S
  • “just sum up all the loads”
  • “just sum up all the loads except wind and seismic”
  • “just sum up all the loads except point & moment loads”

So with that in mind, we want to avoid any ambiguities. This is why we call it “Simplified DL + (LL or SL)” deflection check. But your point about users potentially being unaware that “Critical Deflection” doesn’t include dead load is well taken. We’re going to see about making this more obvious.

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The check box is a good solution. And it is good to see that the absolute max specified deflection is now compared against the total deflection, where it wasn’t previously. My current house has three failing beams but it is easy to correct that situation.

Is there a way to set a global selection of this toggle so that all future calcs show total deflection? I am sure to forget all about it soon enough.