You can use the Analyze Gravity Network command to resize pipes and reset inverts and to compute the energy and hydraulic grade lines according to HEC-22 standards.
You can use this utility to:
Following is a before and after example of analysis results for a pipe network shown in profile view.
Pipe network before resizing | Pipe network after resizing |
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There are three analysis types you can select: Resize Pipes and Reset Inverts, Compute Energy and Hydraulic Grade Lines, and Inlet Analysis.
The calculations are based on the Urban Drainage Design Manual Third Edition, Hydraulic Engineering Circular No. 22 (HEC-22), published by the U.S. Department of Transportation Federal Highway Administration.
Some prerequisites are required before doing an analysis, depending on the type of analysis you want to do.
You can use the Gutter Details section of the Structure Properties dialog box to define properties of the roadway area around the inlet. These properties are used by the Analyze Gravity Network command for inlet analysis calculations.
Settings that must be specified manually for the tributary areas and pipes, or which are used as values in the analysis calculations, can be pre-established as defaults on the Settings page. Click the Settings button on the General page to open this dialog box.
Default settings for structures can be specified in the Edit Feature Settings - Structure dialog box.
You can map the parameters of parts created with Part Builder to parameters that are required for the Analyze Gravity Network command.
By mapping the parameters and applying them to the structures in existing pipe networks, you will not need to manually specify the values when you are using the Analyze Gravity Network command.
For more information, see To Map Drainage Structure Parameters for Gravity Network Analysis.
Use the Network Details page of the Analyze Gravity Network dialog box to review and change the network detail information that is relevant to the selected analysis types.
If the analysis type you select cannot be performed, an error message is displayed below the Network Details button on the General page of the Analyze Gravity Network dialog box.
If some of the network detail information should be reviewed, a warning message is displayed below the Network Details button on the General page.
Click the Network Details button to open the Network Details page where you can review errors and warnings and change the network detail settings.
For more information, see Network Details Page (Analyze Gravity Network Dialog Box).
When you click the Analyze button in the Analyze Gravity Network dialog box, the Results page is displayed.
Visual cues and tooltips are displayed to indicate the analysis results.
When you select a row in the results table, the right panel displays detailed information about the pipe and structure in the selected line.
For more information, see Results Page (Analyze Gravity Network Dialog Box).
For the Resize Pipes and Reset Inverts analysis type, the Analyze Gravity Network command checks the current part catalog for replacement parts. If a required part size is in the catalog but does not exist in the current part list, then it is added to the current part list after the parts are replaced.
If the analysis determines that a different part size is required, that size will be queried from the original family of the pipe, and if the required size does not exist in that family, other part families that are used in the pipe network will be queried from. This may result in the material of one pipe being changed for a different material (but only if the other material is already used in the pipe network).
If... | and if... | then... |
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the original part is an 18 inch concrete pipe and the analysis determines that a 12 inch pipe can be used | a 12 inch concrete pipe exists in the part catalog | the 12 inch concrete pipe will be used |
the original part is an 12 inch concrete pipe and the analysis determines that a 10 inch pipe can be used | a 10 inch concrete pipe does not exist in the part catalog | then other part families that are used in the pipe network will be queried from for a 10 inch pipe
Note: Notifications are not made when the material of a pipe is changed for a different material in order to match the recommended size. To review the pipe materials, you can output a pipe report or create a table in the drawing that includes a column to show the pipe material.
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