Yesterday while trading messages with a friend we discussed my previous post about columns disappearing. He suspected it might explain the issue he was observing. After looking more closely it turned out that it doesn't. In his situation the structural columns were modeled the full height of the building and Join Geometry was used on walls, that passed through (overlapped) the columns, at each floor (level). The result: at some levels no column appeared while at others they do.
It was necessary to pull the walls back so they stop at the surface of the columns. Join Geometry allowed for the desired appearance and the columns reappeared at the other levels where they were missing earlier.
Showing posts with label Join Geometry. Show all posts
Showing posts with label Join Geometry. Show all posts
Thursday, May 23, 2019
Friday, May 03, 2013
Dominant Elements in Concrete Joins
This information is "ripped" from the WikiHelp topic...
Whenever elements that use concrete for their material interact with each other one element retains its geometry while the geometry of the other element sharing the join is cut to create the appearance of a single form. For example structural floors and walls possess dominant geometry characteristics and always maintain their geometry when sharing a join with other elements. Because of this, they will not automatically join with one another. These other concrete elements behave as follows.
These join behavior rules cannot be changed and it is not possible to disable the automatic joining of geometry. It is possible to manually change this condition using the UnJoin Geometry tool.
While were at it these are the valid combinations for concrete elements to join, in other words they may automatically join with one another.
Whenever elements that use concrete for their material interact with each other one element retains its geometry while the geometry of the other element sharing the join is cut to create the appearance of a single form. For example structural floors and walls possess dominant geometry characteristics and always maintain their geometry when sharing a join with other elements. Because of this, they will not automatically join with one another. These other concrete elements behave as follows.
These join behavior rules cannot be changed and it is not possible to disable the automatic joining of geometry. It is possible to manually change this condition using the UnJoin Geometry tool.
While were at it these are the valid combinations for concrete elements to join, in other words they may automatically join with one another.
- beam to beam
- beam to column
- isolated foundation to isolated foundation
- isolated foundation to wall foundation
- structural floor to beam
- structural floor to column
- structural floor to slab edge
- wall to beam
- wall to column
Friday, March 08, 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?
Thursday, July 14, 2011
The Difference Between Join and Attach
There are two kind of messages that Revit shows you regarding how walls, floors and roofs interact.
The first kind (Attach) occurs when the geometry of a wall touches a floor or passes through the floor. If you edit the sketch of a floor, when you finish the sketch Revit asks you if you'd like to attach this wall (or any other walls that intersect too) to the underside of the floor.
The point of this is to establish an "automatic" relationship between the underside of a floor and various walls. If the floor type (thickness) changes the top of the wall(s) will change as well. If the level the floor is assigned to is raised/lowered the walls adjust accordingly too. It's meant to be "quicker" than manually doing it yourself by selecting walls and using the Attach Top/Base tool. However you may want some walls to do it and others not so much. Many times the "correct" answer is NO.
Here are the results for yes and no responses (note that there is no "joining" of geometry, just the wall height is changed).
Same thing happens when a wall and roof geometry intersects except the dialog message is slightly different.
The second kind (Join) is when a floor intersects a wall, like at exterior walls. Revit asks if you want to join geometry so the cut/projection lines that it draws better represent how these elements would really intersect.
The first message does appear too, just before the second message appears. It's good to choose NO to the first so the wall does not get attached (which would change its height) and then YES so the geometry joins nicely. If you aren't cutting a section through this part of the building then you could argue there is no need to join geometry since nobody will see the clumsy connection between wall and floor.
Now for this message to appear it is necessary to "Pick Walls" and use the "Extend into wall (to core)" Option. If you don't use these then you just get the first message.
If you choose NO for both "questions" you can always use the Join Geometry tool later between any elements that need to "clean up" better. Again the point of this second kind of question is to provide a "speedier" way to end up with a better section(s) when you cut one later.
The first kind (Attach) occurs when the geometry of a wall touches a floor or passes through the floor. If you edit the sketch of a floor, when you finish the sketch Revit asks you if you'd like to attach this wall (or any other walls that intersect too) to the underside of the floor.
The point of this is to establish an "automatic" relationship between the underside of a floor and various walls. If the floor type (thickness) changes the top of the wall(s) will change as well. If the level the floor is assigned to is raised/lowered the walls adjust accordingly too. It's meant to be "quicker" than manually doing it yourself by selecting walls and using the Attach Top/Base tool. However you may want some walls to do it and others not so much. Many times the "correct" answer is NO.
Here are the results for yes and no responses (note that there is no "joining" of geometry, just the wall height is changed).
Same thing happens when a wall and roof geometry intersects except the dialog message is slightly different.
The second kind (Join) is when a floor intersects a wall, like at exterior walls. Revit asks if you want to join geometry so the cut/projection lines that it draws better represent how these elements would really intersect.
The first message does appear too, just before the second message appears. It's good to choose NO to the first so the wall does not get attached (which would change its height) and then YES so the geometry joins nicely. If you aren't cutting a section through this part of the building then you could argue there is no need to join geometry since nobody will see the clumsy connection between wall and floor.
Now for this message to appear it is necessary to "Pick Walls" and use the "Extend into wall (to core)" Option. If you don't use these then you just get the first message.
If you choose NO for both "questions" you can always use the Join Geometry tool later between any elements that need to "clean up" better. Again the point of this second kind of question is to provide a "speedier" way to end up with a better section(s) when you cut one later.
Monday, October 27, 2008
Join Geometry - Crossing Window
When you use the Join Geometry Tool and check the Multiple Join Option (yes the Options Bar) you can use a "Crossing Window" to select multiple items to Join to your first "Pick". Thanks to Ed Tallmadge (Kelar) for the reminder!
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