Understanding structures in Civil 3D involves familiarizing yourself with how Civil 3D models infrastructure components like pipes, manholes, inlets, and other parts of stormwater, sanitary sewer, and other pipe networks. Here’s an overview to help you understand structures in Civil 3D:

1. What Are Structures?
Structures in Civil 3D are components of a pipe network. They represent elements such as:

Manholes: Access points to underground utilities.
Catch Basins/Inlets: Drainage points for stormwater.
Headwalls: End structures for pipes at open channels.
Custom Structures: Specialized parts, such as junction boxes or culverts.
Structures are connected to pipes to form pipe networks for stormwater management, sanitary sewers, or utility designs.

2. Where to Find Structures in Civil 3D?
Toolspace:
In the Prospector tab, pipe networks are listed. Expand a pipe network to view its pipes and structures.
Parts List:
Structures are defined in the Parts List associated with a pipe network. Go to Toolspace > Settings > Pipe Network > Parts Lists to see the available structures.
Tool Palettes:
Structures can be accessed directly in the Tool Palettes (shortcut: Ctrl+3) when editing or creating pipe networks.
3. Understanding Structure Properties
Each structure has specific properties that define its geometry and behavior:

Size: Dimensions such as height, width, and diameter.
Material: The type of material (e.g., concrete, plastic).
Style: How the structure is displayed in plan, profile, and 3D views.
Labeling: Text information displayed with the structure (e.g., name, rim elevation, invert elevation).
To edit a structure's properties:

Select the structure in the drawing.
Right-click and choose Properties.
Modify attributes in the Properties palette.
4. Adding Structures to a Pipe Network
Go to the Home tab > Create Design > Pipe Network.
Click Create Pipe Network from Parts List.
Choose a Parts List containing the structures you need.
In the drawing, place structures by clicking on desired locations.
5. Editing Structures in Profile View
Structures appear in profile views after being added to the pipe network:

Open the Profile View where the pipe network is displayed.
Select a structure in the profile.
Adjust properties like rim elevation, invert elevation, or size.
6. Using Custom Structures
Civil 3D allows the use of custom structures designed in Part Builder. If a required structure isn't in your parts list:

Open the Part Builder from the Manage tab.
Create or modify a structure.
Add the custom structure to a parts catalog and include it in your parts list.
7. Analyzing Structures
Use the Analyze Gravity Network tool to evaluate structure capacities in storm or sewer designs.
Generate Reports for structures:
Go to the Analyze tab > Reports and Tables > Network Structures Report.
8. 3D Visualization of Structures
Use the Object Viewer to see structures in 3D.
Apply realistic styles for better visualization in model space.
9. Structure Labels and Styl