Girder Joist Purlin Assignment Rules

Thanks to for posting this tutorial on their site.

I'm on a REVIT Structural kick right now and quite enjoying it !

I know most of you already had this figured out but not being a structural 'designer' I was a little confused about the 'Structural Usage' property of the term 'Beam'.

Well now I have it figured out and thought I'd pass on what I learned.

1. Girders, Joists and Purlins are all 'Beams'
2. First of all if you leave the Usage as Automatic REVIT will infact assign the correct usage.
3. The structural usage determines the 'linestyle' for 'course detail' visibility. (note the line weights and styles above)
4. The Structual usage can also be specified in a schedule.
5. If you click on on the beam after the fact and check the 'structural usage' property it will tell you what has been assigned and you can change it.
6. REVIT assumes the usage based on what the beam is being connected to at each end.

Here's the rules in a nut shell

Column to Column = Girder
Column to Girder = Girder
Girder to Girder = Joist
Column to Joist = Joist
Joist to Josit = Purlin
Joist to Purlin = Purlin
Purlin to Purlin = Purlin
Column to Purlin = Purlin

ie: Girders are the big ones and Purlins are the small ones.

If you're not sure, try drawing a bunch of Columns and Beams using the 'Automatic' usage then check the beam properties and see what REVIT has assigned !

That's it......next topic.........

R E V I T.. really does ..R O C K !

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