Forums >> Revit Structure >> Technical Support >> bar joist seat depths

minfante

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Joined: Tue, Mar 4, 2008
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Is there a way to esablish a beam system whose bar joists have different start and end seat depths?  I usually assign an offset when creating the beam system that represents on common joist seat depth.

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revitaggie

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Joined: Fri, Aug 27, 2010
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The seat heights don't have anyting to do with the beam system. They are controlled by parameters in the joist family itself. This is why you have to offset either your beam system or your girders to ensure the seats are properly bearing.

In the out of the box form, the joist seats are controlled by a single reference plane. In order to input seperate seat heights, an additional reference plane must be added. Then edit one of the seats (which is modelled as an extrusion). Realign and lock the bottom of the seat to the new reference plane. Change the chord thickness dimensions to reference the new plane. And remember to add a new parameter from the top of the joist to the new refernece plane that describes second joist depth.

Quick summary:

1. rename existing seat depth to "end seat depth" or something appropriate
2. create new reference plane (or copy current one down an inch or so to make it easy)
3. create new parameter to identify new seat depth ("start seat depth") and label the dimension
4. edit the start seat extrusion to align with the new reference plane

I've attached some pictures to help

Attached Images

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seniorcad143

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Joined: Fri, Oct 2, 2009
140 Posts

revitaggie -

Do you have to do this with each joist size you are using?

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Yeesh - Where is My Cad

Yeesh - Where is My Cad

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revitaggie

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It has to be done with each type (e.x.: k-angle web, k-rod web, dlh, slh, etc.). Each specific size takes care of itself through the type catalog which you don't have to mess with.

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seniorcad143

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Joined: Fri, Oct 2, 2009
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For some reason it won't let e align.  It says contraints are not satisfied.  I tried unlocking but it still says that.

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Yeesh - Where is My Cad

Yeesh - Where is My Cad

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seniorcad143

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Joined: Fri, Oct 2, 2009
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For some reason it won't let me align.  It says contraints are not satisfied.  I tried unlocking but it still says that.

Can anyone help with this - I would love to be able to fix this.  I am sure it is probably something that I am just missing.

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Yeesh - Where is My Cad

Yeesh - Where is My Cad

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seniorcad143

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Joined: Fri, Oct 2, 2009
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OK - I got it to move down but I can't get it to align with my reference line.  It keeps picking the shape handle and not the extrusion.

Any ideas?

Attached Images

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Yeesh - Where is My Cad

Yeesh - Where is My Cad

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seniorcad143

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Joined: Fri, Oct 2, 2009
140 Posts

got it - :-)

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Yeesh - Where is My Cad

Yeesh - Where is My Cad

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