To place a joist in Advance Steel, start the Joist tool (Home tab > Extended Modeling panel), pick the start point, the end point and a third point for the height and direction. Advance Steel builds the whole truss (chords, web members and seat plates) and opens a dialog where you set the type, panel spacing, sections and seats.
Joists carry a floor or roof deck and pass the load to the beams or walls they sit on. Below is how to place one, what every tab in the joist dialog does, and what to check when the joist doesn’t come out right.
How do I place a joist in Advance Steel?
Start the tool and pick three points: the start (1) and end (2) of the joist, then a point for its height and orientation (3). After the third point, the joist dialog opens and you can fine-tune everything.
Where is the Joist tool?
Home tab > Extended Modeling panel > Joist
Extended Modeling tab > Structural Elements panel > Joist
What do the joist dialog settings do?
Geometry tab
- Joist name. Used automatically when you save the joist to the library on the Library tab.
- Production. By manufacturer or by workshop. This controls how the joist shows up in drawings and the bill of materials. Most open-web joists in the US come from a joist manufacturer, so the choice matters for what your shop actually has to fabricate.
- Length. Taken from points 1 and 2 by default. Type a value here to override it.
- Height settings. How the joist sits on points 1 and 2. With Top Chords, the top of the top chord lines up with the points. With Support Plates, the seat plates line up with them.
- Height. Taken from point 3 by default. Type a value to override it.
- Type. Pratt (the default), Warren or Modified Warren.
- Opening P. The spacing between the panels (fields) of the joist.
- Decrease number of fields with. How many fields to drop at the ends of the joist.
Chord Extension tab
- Main at start / Main at end. How far the main chord extends at each end.
- Secondary at start / Secondary at end. How the secondary chords extend. Choose Value and type the extension below, As Main to run the bottom chords out to the main chord, or None for no extension.
Sections tab
Pick the sections for the top chord, bottom chord and vertical bars. If you use rectangular sections for the diagonals or verticals, check Rotate to turn them.
Shortenings tab
Set how much the diagonal and vertical bars are shortened at their top and bottom ends.
Joist Seat tab
Settings for the joist seats.
Use plates sets whether you get seat plates at both ends (the default), only one end, or none.
The numbered fields match this sketch:
- Thickness of plate 1
- Length of plate 1
- Width of plate 1
- Thickness of plate 2
- to 8. Projections 1 to 4: how far plate 1 projects past plate 2
Pratt vs Warren vs Modified Warren: what’s the difference?
They’re web patterns. A Pratt truss has verticals and diagonals. A Warren truss has diagonals only, zig-zagging between the chords. A Modified Warren is a Warren with verticals added. Model the pattern the engineer or joist supplier shows. The pictures above show each one.
Should Production be set to manufacturer or workshop?
Set it to how the joist will actually be made. If a joist supplier makes it, choose manufacturer. If your shop fabricates it, choose workshop, so the parts show up on your drawings and BOM.
What to do when the joist comes out wrong
- It’s upside down or on the wrong side. The third point sets the height and direction. Place it again and pick the third point on the side the joist should go.
- It sits too high or too low. Check Height settings: Top Chords lines up the top chord with your points, Support Plates lines up the seats.
- The panels don’t match the drawing. Adjust Opening P and Decrease number of fields with.
- The ends hang past the supports. Check the chord extensions.
Joist sizes, spacing and bearing details come from the engineer and the joist supplier. Model what they give you, and ask if something isn’t clear.
