Problem

How can I set a certain slope for my pipes when designing them? (fixed slope / known slope)

Solution

If you would like to define a specific, known slope and have the constraint based Design tool size the inverts for you, you can set both the minimum and maximum slope constraint equal to the desired slope. 

In the Default Design Constraints or Design Alternative, select the Slope tab in the Gravity Pipe section, and enter the desired slope. This can be done as a global setting to apply to all (or the majority of) pipes, or a "table based" approach where it can be set based on pipe rise (diameter).

If you want to specify different slopes for specific pipes, you would set local design constraints. This can be done either in the Conduit properties (as illustrated below), Conduit Flextable or in the Design Alternative. 

  1) Double click on a conduit to open its properties

  2) Set the "Specify Local Pipe Constraints?" property to "True". See the blue box in the screen shot below.

  3) Set the minimum slope and maximum slope to the same value (or close to the same). See the red box in the screen shot below.  

4) Compute the design run

As an example in StormCAD, set the min and max slope to 0.01 ft/ft in the included Sample_1 model file, located in the Samples folder within the product installation folder.

See Also

Troubleshooting Constraint Based Design Results

Constraint based design only on certain elements

How do I design certain pipes to have different design constraints from those specified in the Default Design Constraints?