1. Modeling Inline Structures using HEC-RAS Version 3.1
March 2003
Modeling Inline Structures using HEC-RAS Version 3.1
HEC-RAS Version 3.1

2. In Line Structures
Can be used to model in-line gated spillways, overflow weirs, drop structures, and dams.
Modeling method is very similar to bridges and culverts.
Weir shapes are either ogee or broad crested.
Gates are either radial (tainter) or vertical lift (sluice).
Up to 10 groups of gates with up to 25 identical gates per group are allowed for each in line weir.
Identical gates must have same type, size, elevation, and coefficient.
Uncontrolled overflow area is also an option.

3. In Line Structures

4. Cross-Section Locations
Suggested cross-section locations are the same as for bridges and culverts.

5. In Line Structure
Typical Cross-Section 2 with ineffective flow areas defined.

6. In Line Structure
Typical Cross-Section 3 with ineffective flow areas defined.
Uncontrolled Spillway

7. InLine Structures
In Line Structure
March 2003
Begin by selecting InLine Structure button from Cross-Section Editor.
Select Lateral Structure button from Cross-Section Editor for lateral weirs.
HEC-RAS Version 3.1

8. InLine Structures
In Line Structure
March 2003
Brings up window similar to culvert and bridge windows.
HEC-RAS Version 3.1

9. In Line Structure Must add structure as first step. InLine Structures
March 2003
Must add structure as first step.
HEC-RAS Version 3.1

10. InLine Structures
In Line Structure
March 2003
Brings up window to input cross-section location of the structure (weir)
HEC-RAS Version 3.1

11. InLine Structures
In Line structure
March 2003
Adds a plot of the upstream cross-section to the window.
Note you can edit the upstream cross-section from this button.
HEC-RAS Version 3.1

12. In Line Structure Click on the Weir/Embankment button...
InLine Structures
In Line Structure
March 2003
Click on the Weir/Embankment button...
Which brings up the Weir Editor Window
HEC-RAS Version 3.1

13. In Line Structure After filling in the data... InLine Structures
March 2003
After filling in the data...
HEC-RAS Version 3.1

14. In Line Structure … the plot is updated to show the embankment.
InLine Structures
In Line Structure
March 2003
… the plot is updated to show the embankment.
HEC-RAS Version 3.1

15. In Line Structure Click on the Gate button...
InLine Structures
In Line Structure
March 2003
Click on the Gate button...
Which brings up the Gate Editor Window
HEC-RAS Version 3.1

16. In Line Structure After filling in the data ... Default values shown C
InLine Structures
In Line Structure
March 2003
After filling in the data ...
Default values shown
Free Flow Condition C TE BE HE C
Under free flow conditions the orifice cofficient is not used. Orifice flow occurs with the submerged condition.
HEC-RAS Version 3.1

17. In Line Structure … the plot is updated showing the gates.
InLine Structures
In Line Structure
March 2003
… the plot is updated showing the gates.
HEC-RAS Version 3.1

18. Chapter 8 of the Hydraulic Reference Manual describes the hydraulic computations through gated spillways.
Chapter 6 of the User’s Manual provides explanation for the various fields of the Inline Gate Editor.

22. Gate openings are input through the Steady Flow Data editor

24. Each profile modeled separately
2 gate groups
All gates opened same height

25. InLine Structures
March 2003
The End
HEC-RAS Version 3.1