tag:blogger.com,1999:blog-1675184707067447729.post3662314562231892033..comments2023-07-12T07:12:04.697-07:00Comments on The RAS Solution: Problems with bridges and culverts.Chris G.http://www.blogger.com/profile/00354834185663924786noreply@blogger.comBlogger210125tag:blogger.com,1999:blog-1675184707067447729.post-4381736619489874242020-02-04T13:19:39.647-08:002020-02-04T13:19:39.647-08:00Hi Chris, I have a situation where I have to do a ...Hi Chris, I have a situation where I have to do a no-rise analysis for a bridge which is bounded by dam upstream and downstream about 800 feet either sides. Can you please suggest what is the best modelling approach?Anonymoushttps://www.blogger.com/profile/10167331657287238215noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-36604807953572555212019-08-01T04:35:35.327-07:002019-08-01T04:35:35.327-07:00Thank you for this very helpful blog! The output ...Thank you for this very helpful blog! The output for an arch culvert I am modeling reports the warning message "During the culvert inlet control computations, the program could not balance the culvert/weir flow. The reported inlet energy grade answer may not be valid.” This only occurs for higher flows with pressure/weir flow conditions and relatively shallow weir flow depth (~1 ft or less). Extreme events (500-yr) do not yield this warning. I have tried adjusting ineffective areas upstream and downstream of the culvert, adjusting the entrance and exit loss coefficients, assuring that my cross sections u/s and d/s of the culvert are spaced closely enough, and adjusting manning's n values, but so far to no avail. The detailed culvert output reports the culvert operating under Outlet Control, which I suppose the program defaults to that if Inlet Control calcs are not valid. Would you have any other suggestions on what i can try to eliminate this warning? Thanks.Doug S.https://www.blogger.com/profile/05008519759953832015noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-62000825903490651172019-04-26T13:47:11.023-07:002019-04-26T13:47:11.023-07:00HI Chris, thanks a lot for your informative blog. ...HI Chris, thanks a lot for your informative blog. One stop destination for HEC-RAS. I am facing an issue for one of the projects that I am currently doing. It is a bridge modeling project. I see that in spite of increasing the bridge opening between corrected effective and revised. There is a hydraulic jump between bridge internals. I have defined the bridge internals separately. The increase in water surface would have been OK if it were a couple of tenth's of a foot. However this model is showing there is a rise of couple of feet. Any help would be appreciated.Adinoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-44783193106977617352019-04-24T09:42:47.515-07:002019-04-24T09:42:47.515-07:00Hi Matt. When you put in culverts you actually ha...Hi Matt. When you put in culverts you actually have 2 upstream distances to worry about. The upstream distance for the culvert (measured from the upstream end of the culvert to the next cross section upstream) and the deck/roadway upstream distance (measured from the upstream side of the top of the embankment to the next cross section upstream). Sounds like you're missing the second of these. Go the the Bridge/Culvert editor, Deck/Roadway Editor, and put in a distance in the box at the upper left titled "Distance". Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-88347783570623355142019-04-24T08:10:51.298-07:002019-04-24T08:10:51.298-07:00Hi,
I'm modelling culverts on two reaches imm...Hi,<br /><br />I'm modelling culverts on two reaches immediately adjacent to each other, and I want to set it up so there is one culvert immediately downstream of the other.<br /><br />I've set the culvert distances/widths to appropriate lengths, which fit between the two cross sections as far as I can tell.<br /><br />I have also set an upstream distance of 1m.<br /><br />However, when I try to run it, there's a problem: it gives the same error message for both culverts: "Bridge/Culvert has an upstream distance of zero, HEC-RAS requires a positive distance between the upstream cross section and the face of the bridge. A zero distance was allowed in versions prior to 3.0. A table was added to the geometric data editor to facilitate global editing of bridge distances and widths. Some length will need to be added to the upstream distance column and an amount greater than that will have to be subtracted from the bridge width column."<br /><br /><br /><br />...This makes no sense to me, as I specifically set the upstream distance as a positive value, and made it such that the culvert size is less than the chainage between the cross sections.<br /><br />Where might I be going wrong?!<br />Mattnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-4662558183924730212019-01-25T10:10:29.541-08:002019-01-25T10:10:29.541-08:00Funny, I was just dealing with this issue yesterda...Funny, I was just dealing with this issue yesterday. If your culverts occupy, or partially occupy the same stationing as your opening (the conspan), then you'll get the error you described. But you also have to use the multiple opening option to make it work right. The work around is to move the culverts outside of the conspan opening and use the multiple opening option. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-88033310040694091352019-01-25T09:14:58.537-08:002019-01-25T09:14:58.537-08:00Hi Chris,
I am hoping you can help with an issue ...Hi Chris,<br /><br />I am hoping you can help with an issue I am having modelling a very large Conspan culvert with two additional overflow culverts. <br /><br />The Conspan has been entered by manipulating the high and low chords of the deck data like a bridge. 2 additional culverts are included at this crossing using the culvert editor. The issue I am having is that HEC-RAS is forcing all the flow through the 2 overflow culverts and not the Conspan opening. It is as if the Conspan opening does not exist. <br /><br />A plan assembly with just the Conspan give perfectly reasonable results.<br /><br />A plan assembly with just the 2 overflow culverts and no Conspan opening gives the same results as the assembly in question. <br /><br />Is there a way to set a primary opening in HEC-RAS?<br /><br />Thank you Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-32137250158899256692019-01-23T15:50:06.244-08:002019-01-23T15:50:06.244-08:00You can filter the points. If it's a lateral ...You can filter the points. If it's a lateral structure, there's a button right in the editor for filtering (in Version 5.0.6). If not a lateral structure, you can copy your 36866 points into a lateral structure embankment table (temporarily) to make use of the filtering tool. Then bring the remaining 500 points back to the embankment editor you're working in. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-67138473533021627832019-01-23T10:06:32.677-08:002019-01-23T10:06:32.677-08:00Hello,
I'm analyzing a crossing and in profil...Hello,<br /><br />I'm analyzing a crossing and in profile view the bridge doesn't have any depth. How is the bridge soffit in profile calculated in HEC-RAS? I'd like to fix the optics in profile, but I also want to makes sure the bridge is coded correctly. Thanks!<br /><br />EmilyAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-14477475005220292292018-09-27T08:17:28.976-07:002018-09-27T08:17:28.976-07:00Hi,
I have trouble selecting a proposed structure....Hi,<br />I have trouble selecting a proposed structure. Here is the situation.<br /><br />I have a existing bridge with no piers, the struture is 22*10 as a box culvert. I created existing condition model and have a 50-Y WSE @ 528.39 and does not meet freeboard & clearance policy. For the proposed condition model, I am using the same cross sections but trying different culvert sizes (2)-15X10's,18x10's.... the WSE's for these sizes is not differing much..I mean it still is around 528.51,61,81,89.... regardless of the increase in span, rise & barrels. How do I design this culvert and meet design freeboard and clearance criteria? <br /><br />Any input is appreciated. Thanks!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-64695284378197857752018-09-25T13:20:20.166-07:002018-09-25T13:20:20.166-07:00Hi Chris,
First of all thanks a lot for your kind ...Hi Chris,<br />First of all thanks a lot for your kind support. Second, I use HEC-RAS for generating bridge rating curves and assign them into a separate Hydraulic-Hydrologic model (ICPR version 4) to simulate stormwater. For a while I was using the structure of four cross sections US and DS of bridge and the related length which is suggested by HEC-User manual. But, I figured out that when I’m using single bridge model with 4 Xsecs and just run the geometry preprocessor, the model doesn’t use Xsec 4 and 1 in calculations, at all. Of course, when I was deleting them I was getting error, but when I was changing them (change the station-elevation, manning values or change the distance to the DS Xsec) there was no change on the rating curves. To solve this problem latter on I was just ignoring Xsec 2 and 3 and the related ineffective areas and instead kept Xsec 4 and 1 (considering to the length of expansion and contraction). With this change in fact Xsec 4 and 1 were replaced with Xsec 3 and 2. Also, I added two dummy Xsecs beyond the mentioned Xsecs to avoid getting error. Do you have any idea about my case? Or do you think my approach is correct. <br />Thanks again<br /><br />Rahman<br />Anonymoushttps://www.blogger.com/profile/11428653252084286197noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-87802044147342630912018-05-24T12:28:23.400-07:002018-05-24T12:28:23.400-07:00Embankment Station/Elevation Table” accepts only u...Embankment Station/Elevation Table” accepts only up to 500 stations values in increasing order. Whereas I have 36866 Embankment Station/Elevation Table. <br />How can we solve this issue, any idea?<br /><br />Thanks in Advance<br /><br />Regards<br />Imran Aziz Tuniotuniohttps://www.blogger.com/profile/05380176024046688597noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-78661595396374253612018-05-21T10:53:51.119-07:002018-05-21T10:53:51.119-07:00It’s covered pretty well with in the manuals. Also...It’s covered pretty well with in the manuals. Also you may want to review some of the example datasets thatbinclud bridges. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-43096300099137197802018-05-19T13:32:27.845-07:002018-05-19T13:32:27.845-07:00Hey chris,
I am new on HEC-RAS,can u tell me how t...Hey chris,<br />I am new on HEC-RAS,can u tell me how to model bridges with side parapet walls and without piers<br />Jackhttps://www.blogger.com/profile/05949455546174094832noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-47529923548832987832018-05-03T19:40:30.149-07:002018-05-03T19:40:30.149-07:00Hard to say over the interweb. Suggest double and ...Hard to say over the interweb. Suggest double and triple checking your input data. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-68662271867856962342018-05-03T10:52:10.665-07:002018-05-03T10:52:10.665-07:00I am modelling a bridge with multiple culverts. Wh...I am modelling a bridge with multiple culverts. When I run my analysis The water surface elevation stays pretty low until it gets to the culverts then it raises and the water is not going through the culvert. Its going on top of the bridge. No matter how low i adjust the elevation it still goes over the bridge deck. Any idea on the problem?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-80182448815857125142018-04-30T09:28:01.422-07:002018-04-30T09:28:01.422-07:00Chris,
I have two flood flows I am examining. Bot...Chris,<br /><br />I have two flood flows I am examining. Both result in the culvert being submerged (both upstream and downstream ends) as well as the road overtopping (weir flow). The total flow (weir + culvert) makes sense, but the amount of flow through the culvert is lower for the higher flood flow. In addition the culvert flow (for both floods) is lower than I expected. <br />Is this reasonable? What is HEC-RAS doing to calculate the culvert flow. Looking at the velocity through the culvert the flow makes sense. I'm just not sure why the velocity is low.<br /><br />ThanksAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-72978082929574063192018-04-21T17:24:17.084-07:002018-04-21T17:24:17.084-07:00Hi Kyle. The profile plot displays the lowest poin...Hi Kyle. The profile plot displays the lowest point on the upper chord definition. This includes the approach to the bridge in the overbanks. If the bridge is perched above the floodplain you may not see it in the profile. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-70603214151669460312018-04-17T16:28:28.762-07:002018-04-17T16:28:28.762-07:00Hi Chris,
Thanks for all your detailed responses,...Hi Chris,<br /><br />Thanks for all your detailed responses, they have been very helpful! I am modeling a three-span county bridge replacement and am having problems with the deck displaying in profile -- it will display low chord but not high chord or deck. Do you have an idea of what might cause this? The reach has very wide floodplains (1000' each side of bank). I've tried extending the deck to match the extents of my cross sections, but haven't had any luck. <br /><br /> <br /><br />Kylenoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-81982395790683089282018-04-09T04:51:02.449-07:002018-04-09T04:51:02.449-07:00I am modelling a bridge and when I attempt to run,...I am modelling a bridge and when I attempt to run, I get the following error "A flow needs to be specified at the top of the reach".Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-13808707253325247422018-02-21T18:38:26.238-08:002018-02-21T18:38:26.238-08:00...cross sections with lids. ...cross sections with lids. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-10129125260185683062018-02-21T18:37:58.529-08:002018-02-21T18:37:58.529-08:00If you want to be able to have two different slope...If you want to be able to have two different slopes, you have to do. Ross sections with lids. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-76989886223296487322018-02-21T10:41:02.508-08:002018-02-21T10:41:02.508-08:00Do I need to make two different culvert and connec...Do I need to make two different culvert and connect them for 2 different slope or can I make one culvert with variable slope? <br />I tried to connect two station of different slope <br />I have st 544.19 to start my culvert with 4.5% slope and other 6.62% slope begins from st 519.19. I have upstream station at 550 now <br />I created first culvert at upstream 544.19 with upstream 550 and tried to create one more culvert at downstream of slope change at 519.19 but I am confuse what upstream distance do I need to enter (as 519.19-519.9=0 or 550-519.19=30.81 and same as width what do u need to enter. I am tried to connect two culvert for my different slope. <br />I tried to make 2 culvert with different slope and try to connect but the second culvert in downstream that I wanna tie with first one I am confuse in upstream distance do I need to put zero <br />my different in slope distance is 25ft (544.19-519.19) and remaining length is 112 ft <br />could you help me ? <br />or can I do lid in cross sextion and make different slope so that one culvert will solve my issue? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-41926714826987251522018-02-21T09:01:47.446-08:002018-02-21T09:01:47.446-08:00You can’t have two different slopes. You can eithe...You can’t have two different slopes. You can either use a single representative slope, or if it is really important to show two different slopes, you can build the culvert out of cross sections with lids. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-85705675831887307642018-02-20T13:48:14.092-08:002018-02-20T13:48:14.092-08:00Chris,
I have a problem regarding culverts. I have...Chris,<br />I have a problem regarding culverts. I have a culvert that has been proposed to run with different slope inside the culvert. I have a culvert with 25 ft with 4.5% slope and 6.62% slopw with 115 ft. how can I draw a culvert with different slope? I tried to connect as a series with two culvert but I got a error Anonymousnoreply@blogger.com