Purlins are secondary framing sections equally spaced and placed on top of the rafters. The purlins are used to provide additional support for the roof deck.
You can access this tool from the Home tab:
Home tab > Extended Modeling panel > Purlins
Or from the Extended Modeling tab:
Extended Modeling tab > Structural Elements panel > Purlins
Using the Purlins Tool
When you click on the purlins tool, you will be asked to select all the supporting beams. Select all the rafters on which you want to place the purlins and press ENTER. You will then be asked to select a reference point and if you want to select an additional reference beam. Once you answer all of these questions, a dialog box will open where you can tweak the purlins.
Sections Tab
In this section, you can specify the sections of the purlins.
Section Size
Specify the type and size of the section of purlins here.
Heavy End Bay
Check this box if you need to make the end sections heavier than the middle sections:
Heavy End Size
Select the type and size of the section to be used as an end purlin.
Span Type
Select the span for the purlins. By default, “Single Span” is selected. The other options are: right or left hand with swaps, single, or centered.
Model Role
Define the model role of the section. The default value is “Cold Rolled Purlin.”
Overlap
If you want your purlins to overlap, check this box.
Alignment Tab
This section is used to define the alignment of the purlin sections.
Reference
Define the reference for placing the purlins. The default value is “System Line,” where the purlins will be aligned to the system axis of the end rafters. The other option is “Outer Edge,” where the purlins will be extended to the outer edges of the end rafters.
Stub
Specify here if you need to insert additional purlins to extend outside the end rafter sections. The default value is “None.” If applied, no additional sections will be inserted at the ends.
Stub Length
This option is activated if you will be inserting stub sections at one or both ends. It acts to define the length of the section.
Overhang First Support
Use this feature if you want to create an overhang on the left side.
