RAM Connection Gusset Plate design issue

Hi 
I am trying to design a brace column connection with a base plate. I am using the smart gusset plate option to design in RAM connection. The frame was imported from a design that was completed in RAM frame. I am using a W 10x33 for my column and if I set the base plate dimension to 16"x16" the design is being reported as inadequate and it cites section DG1 B.4.1 and it requires the dimension to 15.73"x26.22". I checked the code and it requires the 15.73x13.96 (bf +2*3). Am I missing something here? Is there an actual bug in the code?

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  • I take it the gusset plate frames into the column web here.  If so, then it's the Nmin dimension that is coming out larger. It's using

    Nmin = drigid + 2/*3 ,

    where drigid is affected by the LH (length over plate) dimension of the gusset. I can get your results only when the LH is very small.



  • Hi Seth

    Thank you for replying. Yes, the gusset plate frames into the column web here. The minimum dimension of the base plate are N> d+(2*3) and B > bf + (2*3) based on the code this gives me the dimensions 15.73x13.96 for a W10x33 . I am confused on where the formula you mentioned is coming from. Can you please clarify?
  • Right, and if there is no gusset plate welded to the base plate, then that's what we come up with, but when there is a gusset plate it's something like this:



  • On your derivation, why does LH_R come into play for determining N_left, and LH_L for determining N_right? Shouldn't those subscripts be reversed?
    Also, where is the 3" dimension coming from? Is that just you guys interpreting the examples in AISC DG1 as a hard rule? If so, you probably shouldn't be flagging baseplates for failing a minimum not required in the design guide.
  • I probably did reverse my subscripts. Yes, 3" extra is inferred from the examples. It's just a warning though, not a failure.



  • Inferred, but certainly not required. And I've had clients (practicing engineers) interpret the big red X as a failure. And there is nothing to indicate it's a warning instead of a failure, just a "minimum value" (that isn't really a minimum), and a big red X under the Status column. How else should they interpret that? So then I have to respond back after they've rejected my calc submittal to explain that if they look up your DG1 B.4.1 reference, they'll see that there is no requirement there, and that that check in the calc output is just a bogus check that I forgot to delete out. Where I typically see this come up is with perimeter columns where the back side of the baseplate needs to be close to the column, but it is relatively unrestricted on the sides, so the anchors are placed outside the column footprint where that whole 3" recommendation is a moot point. See the screenshot below as a typical example where the anchors are clearly in acceptable locations, but RAM Connection still generates a warning/apparent failure.

  • We got some confirmation from AISC that the initial 3" minimums refer to concrete cover and don't need to be enforced in the final checks since we are already checking that in the anchors section. We will revise the report in the next version.



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