Thursday, October 31, 2013

Column and Beam Relationship Macro Idea

I wrote a post that described the parameters (Start Attachment Type and End Attachment Type) that can be harnessed to make beams respond to column changes, specifically the height of the column to cause a beam to slope. While chatting with some Revit Structure users it occurred to me that it would nice if a macro existed that could automate the process a bit. As it stands now we often need to deal with each beam carefully to determine which end of the beam is actually attached to the column. It is easy to see now with the addition of colored ends (green for start and red for end) when Show Analytical Model is used.

That written, we could just select all of the beams, say for a roof structure, and change both parameters, Start and End Attachment Type, from End Elevation to Distance. If their supporting column's Top Constraint or Top Offset values don't change then the beams won't either. In that context it's not hard to just select them all and apply the same parameter values regardless of whether they will need to change or not.

If we want to be more selective, I imagine it would be nicer to start a macro, select a column and let the macro determine which end is connected, for each beam, and alter the required parameters. Alternatively the macro could let us select beams and then the related column we want the beams to follow. Ideally the macro could let us choose between the two approaches. Technically the macro doesn't need to know which column to change the parameter if we just want to change both parameter values. It matters if we'd prefer to only change the parameter relevant to a specific column.

Perhaps such a macro exists individually or as part of a collection I haven't noticed yet? If so, enlighten me. If not I'd be happy to brag about the developer that creates it. Second it even worthwhile?


Jon Brazier said...

Steve - I wish there was a macro for this also since you cannot select all beams and change the Start and End Attachment parameter in one fell swoop. The "Attachment" parameter only exists for beam ends that connect to a column. If a beam connects to a column at both ends the Start and End parameters exist, if a beam connects to only one column the parameter exists only for that end, if a beam frames between 2 beams the parameter doesn't exist at all. Since a typical framing plan consists of all of the above conditions when you select all beams the 2 parameters do not show in the instance properties. This reinforces your idea for a nice macro.

Unknown said...

Steve- This is still not a 100% solution, at least in '14, but it's oh so close. Where I'm still stuck is when the beams AND column need to drop 2/ 1/2" when they support joists. I like to set my top of columns to the deck bearing elevation and then place my beams from top of column to top of column using a z offset of -2 1/2". That's perfect for a k-joist beam system and when I change the top of column elevation, the column and beam and joists all change correctly. The problem is when a joist falls on the column line and the seat overlaps the column. In this case, the top of column really needs to drop the same 2 1/2" but I can't do that without the beams dropping an additional 2 1/2" and taking all the joists with them. This seems like the top "node" of the column really should be at the deck bearing elevation but the graphical column would drop. The z-offset, and attachment type settings of the beams essentially works like this, you would think the column would too.