Modeling Inline Structures using HEC-RAS Version 3.1

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Modeling Inline Structures using HEC-RAS
Version 3.1
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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.

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In Line Structures
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Cross-Section Locations
Suggested cross-section locations are the same as
for bridges and culverts.
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In Line Structure
Typical Cross-Section 2 with ineffective flow
areas defined.
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In Line Structure
Typical Cross-Section 3 with ineffective flow
areas defined.
Uncontrolled Spillway
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In Line Structure
Begin by selecting InLine Structure button from
Cross-Section Editor.
Select Lateral Structure button from
Cross-Section Editor for lateral weirs.
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In Line Structure
Brings up window similar to culvert and bridge
windows.
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In Line Structure
Must add structure as first step.
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In Line Structure
Brings up window to input cross-section location
of the structure (weir)
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In Line structure
Adds a plot of the upstream cross-section to the
window.
Note you can edit the upstream cross-section from
this button.
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In Line Structure
Click on the Weir/Embankment button...
Which brings up the Weir Editor Window
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In Line Structure
After filling in the data...
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In Line Structure
the plot is updated to show the embankment.
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In Line Structure
Click on the Gate button...
Which brings up the Gate Editor Window
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In Line Structure
After filling in the data ...
Default values shown
C
Free Flow Condition
TE
BE
HE
C
Under free flow conditions the orifice cofficient
is not used. Orifice flow occurs with the
submerged condition.
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In Line Structure
the plot is updated showing the gates.
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Chapter 8 of the Hydraulic Reference Manual
describes the hydraulic computations through
gated spillways. Chapter 6 of the Users Manual
provides explanation for the various fields of
the Inline Gate Editor.
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Gate openings are input through the Steady Flow
Data editor
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Each profile modeled separately
2 gate groups
All gates opened same height
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The End