Creating Duct Banks Using the Subassembly Composer

In Subassembly Composer, we are building subassemblies of course. We do this when we have a need for a subassembly that Civil 3D does not provide.

In my experience, Subassembly Composer has come in very handy when working with concrete-encased duct banks. One duct bank can change its cross-section several times along an alignment. That’s why corridors are great features for modeling duct banks.

Duct bank corridors can be easily modified vertically with its corresponding profile.

Subassemblies for duct banks can be coded to ensure like geometry transitions properly to a change in cross-section.

Subassemblies for duct banks can be coded so that quantities can be extracted.

• The center of each conduit in section can be coded so that conduit lengths can be quantified:
• • • How much 6” PVC is needed?
    • How much 4” PVC is needed?
    • How much 8” Steel Pipe is needed?

• The coding of each conduit center also allows the conduits to connect up when transitioning to another duct bank assembly.
• The shape of the conduit can be coded so that average end areas and ultimately volumes for concrete can be quantified.

Assemblies with duct bank subassemblies also look very nice in cross-sections.

Let’s start out by creating the outline of a simple concrete-encased duct bank.

To create a custom subassembly in subassembly composer:

1. In the lower right corner panel of Subassembly Composer on the Packet Settings tab, name the subassembly. Remember that no spaces are allowed in the subassembly name.

2. In the lower right corner panel of Subassembly Composer on the Input/Output Parameters tab, create the custom parameters necessary to connect the 4 corners to any duct bank section that will follow in the corridor. Create the CONC parameter for the eventual quantification of concrete volumes.

3. From the Tool Box panel , drag and drop a Point onto the Flowchart panel. Consider this the attachment point i.e., the point on the subassembly that will be attached to the assembly base line which ultimately attaches to the alignment/profile.

4. From the Tool Box panel, drag in 4 more points. These will automatically be configured to create links which will represent the segments forming the outer edges of the duct bank in section. Drag in a Link which will close the shape of the duct bank encasement.

5. In the Properties panel, configure the new flowchart contents as follows:

6. From the Tool Box panel, drag in a Shape and configure the Properties panel as follows:

*The green button to the right of the Links field allows you to pick inside of the rectangle of links in the Preview panel thus automatically selecting the links needed.

Save the subassembly.

Thus far, we have created a duct bank. Next, we’ll create conduits within the duct bank.

7. In the lower right corner panel of Subassembly Composer on the Input/Output Parameters tab, create the parameters needed to code the center of the conduits for the purpose of quantifying total length of conduit and connecting the centers of the conduit in each cross-section.

8. From the Tool Box panel, drag in 6 points into the Flowchart Panel. These points will represent the top, center, and bottom of each conduit in this example.

9. In the Property panel, configure each point as follows (note that each Link checkbox is not filled):

10. Drag in 4 Curves from the Tool Box panel. These will drop in as Links in the Flowchart panel.

11. In the Properties panel, configure each Link as follows:

To create a shape representing the concrete duct bank encasement without the cross-sectional area of the conduits, do the following:

12. From the Tool Box panel, drag in a Shape.

13. In the Properties panel, configure the shape as follows:

*Remember to use the green button to pick inside of the duct bank avoiding the conduit shapes.

14. Save the file.

The preview should now appear as below:

The following video shows how to import this subassembly into Civil 3D for use in an assembly.

 

Custom subassemblies can come in handy when the stock subassemblies do not offer what we need. Using them can help to contribute to the overall dynamic functionality of our models. With Subassembly Composer, creating one is not necessarily difficult. Please stay tuned for upcoming posts to further demonstrate the use of custom subassemblies and how they affect our designs.

 – Cyndy Davenport