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.
Showing posts with label Beams. Show all posts
Showing posts with label Beams. Show all posts
Thursday, July 4, 2013
Friday, March 8, 2013
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?
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?
Monday, April 16, 2012
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.
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