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The model used in this example contains roof beams and purlins.

How are purlins correctly positioned on roof beams

How are purlins correctly positioned on roof beams

At first, the bars are placed relative to their central axis:


To place the purlin on a beam:
  • Select the beam and modify the eccentricity to 0,-z in the properties window.
  • How are purlins correctly positioned on roof beams


  • Select the purlin and modify the eccentricity to 0,+z in the properties window.
  • How are purlins correctly positioned on roof beams

  • Slope the purlin placing its lower flange on the beam upper flange. You can choose between two methods:

How are purlins correctly positioned on roof beams 1. Measure the slope angle of the beam, then rotate the purlin by this angle:

- To measure the slope angle, use the Ctrl + G shortcut, and then select three points in the model that describe the measured area. In our example, the measured angle is 45 degrees.


- Modify the purlin orientation angle to 45 degrees in its properties window.

How are purlins correctly positioned on roof beams

2. Rotate the purlin using a user defined reference point. This method is best when the beams are sloped at different angles.
How are purlins correctly positioned on roof beams

- Define the reference point at one of the beam's ends (in this case, at the upper end). The created point is automatically numbered with "1" (if it is the first point created in the model).



- Select the purlin. Enter the point ID in its properties window as shown below, to define the purlin orientation by point. The purlin's y-axis will slope towards the specified point.

How are purlins correctly positioned on roof beams


- Modify the purlin orientation angle.

How are purlins correctly positioned on roof beams

The beams and the purlins are now correctly positioned.

How are purlins correctly positioned on roof beams