product focus
AutoCAD Civil 3D
2012
to the assembly or other subassemblies. Select a side (left, right or none) in the Input/Output Parameters tab. Determine what Point, Link, and Shape codes and Targets, Variables, Inputs, and Outputs will be needed. Figure out if you’ll need Decisions or Switches. It may be helpful to sketch your flowchart on a piece of paper. Build a neat and logical flow chart. Start building your flowchart from the origin point. I like to label my points on a print-out—it helps me build my points in a logical order. Use Sequences to collect a series of Points, Links, and Shapes into a logical group. Copy and paste sequences that represent alternate cases (Switch or Decision outputs) reusing point, link, and shape names. Test your subassembly in the preview window by dragging the targets. Test left and right side functionality and other inputs. Choose Point, Link, and Shape codes carefully. Use standard Civil 3D point, link, and shape codes Figure 1: The Subassembly Composer for AutoCAD Civil 3D.
Applications of the Subassembly Composer include retaining walls, rail track, tunnels, guard rail, concrete barriers, rock benching, bridge beams, and duct banks. The CalTrans standard Type 1 retaining wall is a great example of the power of the Subassembly Composer. It is relatively straightforward to create a retaining wall subassembly that varies the footing dimensions and key location with the wall height, while the wall height varies based on a surface or elevation (top of wall profile) target. Subassemblies can be developed that also target horizontal offsets (alignment, feature line, or polyline) and react to superelevation. The only relational link that is unsupported by the Subassembly Composer is the link to pipe networks as used in the stock TrenchPipe2 subassembly. The Subassembly Composer supports circular and parabolic arcs, daylight roundings, and fillet arcs. All curves will be tessellated, but the user specifies the level of tessellation (i.e., number of chord segments). The level of tessellation can be hard-coded in the subassembly or included as a variable to be specified within Civil 3D. The ability to create dynamic curved links and a very high level of tessellation has numerous applications from pressure pipes to tunnels.
Workflow with the Subassembly Composer Plan your Subassembly. Decide on your origin point before you start building your subassembly. This is where your subassembly will attach 20 www.augi.com
Figure 2: P3 location defined mathematically using input parameters for pipe diameter and wall thickness.
where applicable to support surface, feature line, and quantity takeoff applications. “Top” and “Datum” link codes have special meaning in surface creation, but you will get yourself into trouble if you assign these codes to vertical links. Shape code names are especially important if you will be using the Corridor Solids tool. It is possible to use an input field for your code names for the designer to specify them when using the subassembly in Civil 3D. Review the Packet Settings tab. You need to give your subassembly a unique name. The name will ultimately appear on your tool palette December 2011