HEC-RAS Bridge Modeling

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Lee
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HEC-RAS Bridge Modeling

Lee
I have a model where we have several bridges that span over a concrete channel.  The channel stations above and below the bridge sections are consistant with uniform slope and cross-section.  The cross-sections below the bridges or above the bridges, the flow stays within the channel.  For some reason when I analyze with steady flow, I have large hydraulic jumps at the bridges in my upper section?  I know the data is incorrect.  I've changed locations of the cross sections 2 & 3 and get similar results.  I've changed the bridge modeling approach which has no affect on the results.  I've rechecked the cross-sectional data and bridge deck data.  I'm out of ideas.  Any solution?
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Re: HEC-RAS Bridge Modeling

jadams
Have you checked out Chris's post about bridges.  Even though it seems you have already re-evaluated your geometry I would still start with the post.
http://hecrasmodel.blogspot.com/2009/08/problems-with-bridges-and-culverts.html
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Re: HEC-RAS Bridge Modeling

Chris G.
Administrator
In reply to this post by Lee
Hi Lee-

Can you post a screen shot of what you are talking about?  What does your bridge opening look like?  Is if very small relative to the channel size upstream and downstream?  Also, you said it's a concrete channel.  Is it flowing supercritical?  
Chris G.
@RASModel
www.therassolution.com
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RE: HEC-RAS Bridge Modeling

lzeger

 

Hi Chris,

 

Prior to the first bridge, it only has a Froude # of 0.57 to 0.38, however after the bridge the Froude # jumps to 1.0 so I would class it as subcritical flow.  All three bridges that illustrate the large hydraulic jump above span over the concrete channel.  As shown above, the bridge opening is larger than the stream channel size.

 

From: Chris G. [via HEC-RAS Bloggery Forum] [mailto:[hidden email]]
Sent: Friday, April 26, 2013 11:08 AM
To: lzeger
Subject: Re: HEC-RAS Bridge Modeling

 

Hi Lee-

Can you post a screen shot of what you are talking about?  What does your bridge opening look like?  Is if very small relative to the channel size upstream and downstream?  Also, you said it's a concrete channel.  Is it flowing supercritical?  


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RE: HEC-RAS Bridge Modeling

Chris G.
Administrator
The image doesn't show up on my computer.  Did you use the "Insert Image" above the message window?  That will allow you to insert an image like this:

Chris G.
@RASModel
www.therassolution.com
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