I'm assuming that by the culvert cross sections, you are talking about the bounding cross sections (cross sections 2 and 3, in HEC-RAS "lingo"). I have tried changing the modeling approach and all of the other variables I can think of. I have a situation where the wselev jumps up a couple of feet in the culvert cross sections compared to the upstream and downstream cross sections. Ineffective flow areas upstream and downstream of the crossing. Coefficients (bridge and culvert coefficients). Things you can tweak that may provide more sensible results and a better set of Htab curves are: Not a bad technique, but obviously didn’t completely solve the problem. It appears that the creater of this model tried to lessen the impact of the ineffective flow areas instantaneously turning effective by significantly raising up the n-values in the overbank. Also, notice that the ineffective flow triggers turn off in this range. It’s very obvious from looking at the plot that this is the range at which the flow transitions from low flow to pressure flow and then on to pressure and weir flow. This example shows a significant discontinuity at around 10,000 cfs (you can click on the figure above to get a better view). First of all, I always like to open up the bridge plot along side its htab plot (make sure the vertical axis is consistent) so that I can graphically explain any discontinuities in the htab curves. Take the following example, in the figure below. Also, keep in mind that the equations for culverts are very different from those used for briges in HEC-RAS. going from low flow to pressure flow, or pressure flow to pressure and weir flow), or when ineffective flow triggers turn off/on. Typically you see problem areas where RAS changes equations (i.e. Here you’ll want to examine the curves and look for any abrupt changes, or discontinuities, particularly in the range of flows/depths where you are seeing the discrepancy. Click Type…Internal Boundaries, and you’ll see the family of rating curves for your crossing.
Once that’s done, on the main RAS window, go to View…Hydraulic Property Plots. If you are running a steady flow model, you can create an unsteady flow plan and just run the geometry pre-processing task (you don’t need to run the computations or the post-processing. If you are running unsteady flow, this is done for you during the geometry preprocessing task.
Create and evaluate the hydraulic property plots for the crossing. 2.5 m AC E C G 2.5 m Since each member of a truss can only experience forces at each of its two ends and nowhere else, all members of a truss are referred to as members.For the first case, “bad geometry”, here’s a technique that can be used to help spot sources of problems. Answer the following questions about this particular structure. You begin to think about this structure composed of many different members connected together and how it must have something to do with there being no support columns for the bridge.
You look out your driver window and see the structure shown below. You also notice that on top of this bridge is a metal structure through which you drive as you cross the bridge.
The only place the bridge is supported is on either of its ends at the banks of the river. As you come upon the bridge, you notice that there are no support columns below the bridge for the entire span. You are driving along a road and pass over a bridge over a river. Once an answer is submitted, you will be unable to return to this part. Transcribed image text: NOTE: This is a multi-part question.