CIP Beams

[David Harrington]

Hey all,

What is the trick to get CIP beams to appear hidden on plan, have a modeled/spec depth from top of slab to bottom of beam and to be joinable to the slab in section? I seem to get one or two of these to work but not all 3. The beam edges in plan typically show solid. Grrrrr!

Thanks!
David

[kmarsh]

I managed to reproduce your issue. It seems like RS should know that, once you've joined the beam to the slab, the beam lines (below) should show as hidden.

One work-around would be to use the linework tool (looks like a calligraphy pen on the toolbar). Select <Hidden> in the options bar and click each beam line twice. (you are changing the visibility of each line that makes up the intersection, the beam line and the slab line.) Then you will have the general look that you want to achieve.

In the attached files, I've shown the plan view after the join (I also joined the walls to the slab and they came out hidden, why not the beam??) Then the plan after using the linework tool.

Hopefully somebody else will have some other suggestions too!

[David Harrington]

Thanks for the reply! I tried that route but it required too much effort. The winning comdo seems to be to set the Visability for the object type to be hidden, thus showing dashed lines for the beams in plan - even if they have no slab. Then I join with abandon and have full depth beams. I still need to use the line work tool on occasio, for beams outside of the slab that need to show solid. But that happens much less that the reverse method.

[kmarsh]

(that would be the other suggestion) I actually tried looking through vis/graph to see what I could switch to hidden but I'm finding that the options in vis/graphics aren't necessarily intuitive (for me). Which item did you change and did you change the "projection" or the "Cut" (or both) I was hoping for something like "concrete beams" but it wasn't obvious. (I'm still in demo (read "play" here) mode.
thanks!
-ken

[Jos Arpink]

The thing is that Revit will show hidden lines as long as it recognizes one element as being beneath the other (and the view's discipline is set to "Structural")

There's a thread on this subject that goes back a couple of months:

http://forums.augi.com/showthread.php?t=24071&highlight=display+hidden

Rather than defeat Revit's handling of this by forcing linework, I sort of got around it by creating my own Concrete Beam family.

If you've delved into creating/modifying families, try this:

Start with the beam family that comes from the factory.
Modify the sweep so that it does not go to the top reference plane.
Control this distance with a new parameter called "Slab depth", or something like that.
The parameter for the beam's depth, 'h', remains unchanged. But the depth of the concrete that Revit models is reduced by "Slab depth".

Unfortunately, Revit will still try to suck the beam's "top of concrete" up to the associated level, reducing its intended depth by the new "Slab depth" parameter. This is bad, bad, bad. To compensate, I further modified the family by putting in a single model line of depth 'h'. This forces the beam's geometry back into place, and it works pretty well.

All of this does not mean that Revit shouldn't do a better job of this "out of the box". Hope this helps!

[Jos Arpink]

To expand on this, I've taken the general approach of modelling all concrete walls, columns, and beams (see previous post) so that their top is 6" below level. Then, when I add a slab of some depth (usually more than 6") I don't have to worry about hidden line representation. Revit will take care of it.

Perfect? No.
Reasonable workaround? Maybe.

[David Harrington]

And then I have to wonder how many of these workarounds end up breaking the possible use/import into Etabs and such. Generally analysis programs require things to hit the same nodes in order to function. This means the beam end has to 'be" at the cl of the column. So now I have to tinker with where the column ends and the associated floor, since it has to match as well. Geez, this ain't easy...

[Jos Arpink]

Yes, I agree. I try to keep and eye on how the analytical model develops as I work-up the physical model. It's not just drafting (my background) anymore, is it? Lots to think about.

Etabs, for example, lists which parameters are passed on during an import/export. I would hope that as long as we respect those in our workarounds/solutions, things should be okay. Waiting for the release version of Etabls 9 to put this to the test.