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 guessing...is it even worthwhile?

Beam Joins

Quick tip Thursday: The shortest beam in a join will force the longer beam(s) to cutback. In other words the shorter beam will not cut back. We can use the Beam/Join Editor to adjust relationships.

Concrete Volume between Slab and Beams

A message via Linked In arrived the other evening asking about the volume of concrete when slabs and beams are involved. The hopeful question hinged on the slab reducing its volume by however much the beam overlapped the slab. The answer is a qualified "yes" because it is aware when Join Geometry is used but in the opposite direction, beam reduces volume not the slab.

Here's a floor slab that is 20'-0" x 20'-0" x 6" thick and a 12" Wide x 24" Deep x 20'-0" long concrete beam reporting a volume of 200 CF and 40 CF respectively, before using Join Geometry (slab properties shown).

Here's the properties of the beam before Join Geometry as well, reporting a volume of 40 CF.

Here's the properties of the beam after Join Geometry, now reporting a volume of 30 CF.

I didn't bother capturing an image of the floor slab, its volume didn't change, still 200 CF. I hope you'll take my word for it. The point of the exercise is to determine how much concrete is really needed, at least in my mind. The floor slab volume is intact (for this particular condition at least) but any beams that are joined with the slab will reduce their volume appropriately.

That means a two schedules, one for slabs and one for beams, should provide a reasonably close total if you look at both schedules together. It might be cool if the slab could inherit the beam volume and report a total that included the beams or the reverse subtract the beams from the slab.

In the field the beam and floor, minus any topping slab, are often poured together so the reinforcing ties it all together. Curiously, the way Revit deals with beam sizes and types is generally in conflict with how engineers think of the beam size as it relates to the slab. It's never simple or easy is it?

Two Minutes with Beams and Columns

Brian Mackey recently wrote on his blog about a subtle feature that seems to have crept into the product without much fanfare. You can read his account. I decided to capture it in video format to pass along to a client who was asking about the concept (having beams aware of column ends) so I've posted it here too.

Dept. of Subtle - Offset Elevations at One End

This post has a Revit Structure bias. When you want to offset the end of one beam to slope framing it isn't obvious which end is which. There is a Start Level Offset and and End Level Offset.

When you examine the properties dialog you see them listed nicely but when you just look at a beam there isn't anything obvious to tell you which end is which. Even if you understand which end comes first you probably won't remember how you placed the beam later when you want to change it.

I recall someone telling me that they have everyone sketch left to right and top to bottom so that the Start Level offset is always at the left and top of a beams. Good luck with that! 8-).

If you select a beam however the offset parameters are displayed and if you place your cursor over the offset value you'll get a nice useful tool tip!

For you VIDEO minded folks here's one.