Tuesday, January 13, 2009

Beams with sloped edges

Steven Debooy, a fellow blog reader, recently asked me if it was possible to add a parameterized void at the end of a beam to cut it at a slope. That question prompted me to write this post about how one can achieve that result.

a) Adding a void to the beam is a possible solution. I posted a family in the Structural AUGI forums in 2007. Feel free to reverse engineer it and find out how it works. My example has 2 voids instead: one handles positive angles and the other handles negative angles. The user inputs an angle in one parameter, and 2 calculated parameters evaluate that input and return the correct result.

Voids in beam

b) In the 2009 Revit family of products, one can use the Opening by Face tool to achieve the same result. Using this tool to cut the end of a beam, one will get a warning stating that "Opening partially cuts its host". It's not a serious warning (I guess), but it is meant to inform the user that something could potentially be wrong, as usually an opening is meant to have beam material surrounding the entire sketch perimeter! This is the best option if you want to create custom shaped cuts on the fly.

Opening by face

c) This method makes me mad. Why? Because it's only available in Revit Structure (come on people!). NOTE: As of the Subscription Advantage Pack, this functionality is also available in RAC2010. Thanks Factory!  Aaaanyway, You can sketch a reference plane and then use the Cut Geometry tool to trim the beam against the reference plane (actually you can also trim against a grid). Non-linear cuts are not possible with this technique.

cut geometry


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11 comments:

Bjorn said...

Thanks for all the helpfull tips so far.

1 Question though, the cut-a-beam with a RefPlane method seems to be a view specific method.

Any experience in this?

Dave Baldacchino said...

It cannot be view specific. You're operating on the actual model geometry. None of the techniques mentioned are view-specific. They affect the model in all views.

Marcel said...

The-cut-a-beam with a RefPlane method is not working for me. I use the following method: in moddeling -> Opening -> Opening By Face.

Dave Baldacchino said...

It ONLY works in Revit Structure.

hectorru said...

Hi, the cut geometry only works for metal beams How would do that for reinforced concrete beams? I tried but it appears the following warning: "Cuts on concrete members Are Ignored"

Dave Baldacchino said...

Just use the Opening by Face tool. I don't know why there is a limitation for concrete beams when using the cut geometry with ref. plane (or other datum) technique.

Anders said...

I have the same problem but it appears when I draw a TTF concrete beam and want to cut off a bit of the end, for example around a coulumn. The problem is that its looking good in the 3D-view but in plan view I still se some lines, it looks like it just has cut off a part of the TTF beam.

Anders said...

I have figured out what my problem is. The lines that I see when I cut my TTF concrete beam is the 2D representation of it. The question is now how I tell revit to cut these lines too. One way to solve it is to make these lines invisible in the family but if I do that I'll get lots of lines in the plan view and my drawnings will look messy...does anyone have the solution to my problem?

Anonymous said...

It's interesting that cutting a beam with a reference plane works until you group some beams. Then it looks like it will work for only one group instance at a time. Anyone else running into this behavior?

Deepak Yadav said...

Beam structure really plays important role in pre engineered buildings.

Newton Wong said...

Thanks, Dave! Option B is the perfect solution for making a simple angled cut to the end of my wood beam.

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