Adjusting Joist Seat Depth Separately on Each End

I had a support request recently where we discussed how to adjust the web joist families so the seat depth could be modified separately on each end (by default both ends are controlled together with one parameter). I thought it was a valuable topic to write a post on.

For my example, I will use the LH-Series Bar Joist. If you open up that family and switch to the Back elevation view, you should see the existing Seat Depth dimension and its associated reference plane:

The first step would be to delete this dimension and reference plane.

Next, select one of the seat extrusions on either end.

Go to Modify Extrusion > Clipboard > Cut, and then Modify > Clipboard > Paste Aligned > Same Place. This will break the existing constraints for the extrusion.

There are a couple of constraints you will then need to add. Go to Modify > Edit > Align to activate the align tool to set the following constraints:

1. Select the reference plane on one end of the extrusion. Then select the edge of the extrusion. Lock this alignment.

2. Select the reference plane on the other end of the extrusion. Then select the edge of the extrusion. Lock this alignment.

3. Select the edge of the member above. Then select the edge of the extrusion that coincides with it. Lock this alignment.

Now, you'll need to add a new depth parameter. Place an Aligned Dimension from the top to bottom:

With the dimension selected, go to the Options bar, select the Label pulldown and choose . Name the parameter as desired:

Now follow these steps for the other side - but choose a different name for the parameter - and you should be able to control them separately.

Comments

[access query scheduler]

cool..are these the new trend in doing architecture and engineering?..GOd, i was so naive

[Stephen Harriosn]

Once you do this, you cant load different joist size. Also, if you do a joist extension
the bottom extrusion does not extend out with the 1-1/4 top chord.