HECRAS Bridges HECRAS xidebi

1. HECRAS BridgesHECRAS xidebi by G. Parodi WRS – ITC – The Netherlands g. parodi WRS-ITC- niderlandebi

2. 4 1 How does a bridge affect the hydraulics?rogor zegavlenas axdens xidi hidravlikaze? • Contraction • konstruqcia • Through the bridge • xidis gaswvriv • Piers • pirsi • Abutments • TaRis/kamaras sayrdeni • Bridge deck • xidis savali nawili • Expansion • gafarToeba 2 3

3. 2 Types of Flow at Bridgesxidis dinebis 2 tipi • Low Flow - Flow where the water surface does not reach the low beam • dabalidineba- dineba, sadacwyliszedapiriaraRwevsxidiskoWs • High Flow - Flow where the water surface reaches the deck or higher • maRalidineba-dineba, sadacwyliszedapiriaRwevs an cdebaxidissavalnawils Q: Is this low flow or high flow? kiTxva: esdabalidinebaaTumaRali?

4. Low Flowdabali dineba

5. Low Flow Bridge Modeling: 3 Types of Flowdabali dinebis xidis modelireba: dinebis 3 tipi

6. Low Flow Bridge Hydraulics: 4 methods of modelingdabal dinebiani xidis hidravlika: modelirebis 4 tipi • Energy - physically based, accounts for friction losses and geometry changes through bridge, as well as losses due to flow transition & turbulence. • energia – fizikur kanonebze dayrdnobiT iTvleba xaxunis danakargi da geometriuli cvlilebebi xidis gaswvriv iseve, rogorc dinebiT da turbulentobiT (areulobiT) gamowveuli danakargi. • Momentum - physically based, accounts for friction losses and geometry changes through bridge. • impulsi - fizikur kanonebze dayrdnobiT iTvleba kritikuli danakargi da xidis gaswvriv danakvirvebi geometriuli cvlilebebi. • FHWA WSPRO - energy based as well as some empirical attributes. Developed for bridges that constrict wide floodplains with heavily vegetated overbank areas. • FHWA WSPRO – energiis kanonze dayrdnobiT, iseve rogorc zogierTi empiriuli atributi. SemuSavebulia xidebisTvis, romlebic gadaWimulni arian farTe mWidro mcenareuli safariT dafarul Walebze. • Yarnell - empirical formula developed to model effects of bridge piers. • Yarnell - empirikuli modeli SemuSavebulia xidis pirsebis efeqtebis modelirebisTvis.

7. Low Flow Bridge ModelingClass A Low Flow - Energy Methoddabal dinebiani xidis modelirebaA klasi dabali dineba – energiis meTodi • Friction losses are computed as length times average friction slope. • xaxunisdanakargisgaangariSebaxdebarogorcsigrZeayvanilisaSualoxaxuniskuTxisxarisxSi. • Energy losses are empirical coefficient times change in velocity head (expansion and contraction losses). • energiisdanakargiarisempirikulikoeficientiayvanilisiCqarismaqsimumisxarisxSi(gafarTovebis da SekumSvisdanakargi) • Does not account for pier drag forces. • arxdebapirsebsdamuxruWebisZalisgaTvaliswineba

8. Low Flow Bridge ModelingClass A Low Flow - Momentum Methoddabal dinebiani xidis modelirebaA klasi dabali dineba – impulsis meTodi • Friction losses are external skin friction = wetted perimeter times length times shear stress. • xaxunisdanakargiarisgarexaxuni= sveliperimetriayvanilisigrZisxarisxSi da ayvaniligadanacvlebisdaZabulobisxarisxSi • Requires entering coefficient of drag for piers, CD • moiTxovspirsebisdamuxruWebiskoeficientisdamatebas

9. Low Flow Bridge ModelingCD Coefficients for Piers • Circular Pier (wriuli pirsi) 1.20 • Elongated piers with semi circular ends (wagrZelebuli pirsi semiwriuli boloTi) 1.33 • Elliptical piers with 2:1 length to width (elipsuri pirsi) 2:1 Tanafardoba sigrZe siganesTan) 0.60 • Elliptical piers with 4:1 length to width (elipsuri pirsi) 4:1 Tanafardoba sigrZe siganesTan) 0.32 • Elliptical piers with 8:1 length to width(elipsuri pirsi) 8:1 Tanafardoba sigrZe siganesTan) 0.29 • Square nose piers (marTkuTxa xmauriani pirsi) 2.00 • Triangular nose with 30 degree angle (triangularuli xmauri 30 gradusiani kutxiT) 1.00 • Triangular nose with 60 degree angle(triangularuli xmauri 60 gradusiani kutxiT) 1.39 • Triangular nose with 90 degree angle (triangularuli xmauri 90 gradusiani kutxiT) 1.60 • Triangular nose with 120 degree angle(triangularuli xmauris 120 gradusiani kutxiT) 1.72

10. Low Flow Bridge ModelingClass A Low Flow - Yarnell Equationdabali dinebis xidis modelirebaA klasis dineba-iarnelis gantoleba • Based on 2,600 lab experiments on different pier shapes • sxvadasxva formis pirsebis gamoyenebiT 2600 laboratoriul eqsperimentze dayrdnobiT • Requires entering pier shape coefficient, K • moiTxovs pirsis formis koeficientis damatebas • Should only be used where majority of losses are due to piers. • unda gamoviyenoT mxolod iq, sadac ZiriTadi danakargi gamowveulia pirsebs arsebobiT

11. Low Flow Bridge ModelingYarnell’s Pier Coefficient, Kdabali dinebis xidebis modelirebaiarnelis pirsis koeficienti K • Semi-circular nose and tail 0.90 • semi-cirkularuli xmauri da kudi • Twin-cylinder piers with connecting diaphrag 0.95 • ormagi cilindruli pirsi dakavSirebuli diafragmiT • Twin-cylinder piers without diaphragm 1.05 • ormagi cilindruli pirsi diafragmis gareSe • 90 degree triangular nose and tail 1.05 • 90 gradusiani triangularuli xmauri da kudi • Square nose and tail 1.25 • marTkuTxa xmauri da kudi • Ten pile trestle bent 2.50 • aTi gaerTianebuli sayrdeni

12. Low Flow Bridge ModelingClass A Low Flow – WSPROdabali dinebis xidis modelirebaA klasi dabali dineba - WSPRO • Federal Highway Administrations method of analyzing bridges • federalurigzatkecilisxidebisanalizisadministratorulimeTodi • Uses energy equation in an iterative procedure • gamoviyenoTenergiisgantolebaiteraciuli (ganmeorebiTi) procedurebisTvis

13. Class B and C Low-flow MethodsB da C klasi- dabali dineba • Two methods available: • ori meTodia xelmisawvdomi: • Momentum - With irregular cross-section data and rapidly changing water surface elevation, the estimate of bed slope can be erratic. Therefore, the weight component is automatically turned off for Class B flow. • Momenti (impulsi) – araregularuli ganivi kveTebis monacemebiT da wylis zedapiris simaRlis uecar cvlilebebiani monacemebiT, SeiZleba kalapitis daxris kuTxis dadgena naklebi sizuzstiT moxdes. Sesabamisad wonis koeficienti avtomaturad gamousadegari xdeba dinebis b klasisTvis. • Energy - During Class B flow, a dramatic change in depth can occur with resulting large changes in velocity head. Contraction and Expansion energy losses may be overestimated with “traditional” contraction and expansion coefficients. • energia – B klasis dinebis SemTxvevaSi, SeiZleba moxdes mniSvnelovani cvlileba wylis siRrmeSi, Sedegad gvaqvs maqsimalur siCqaris agdaWarbeba. gafarToveba da SekumSvis energiis danakargi SeiZleba gadaWarbebuli iyos “tradiciuli” gafarTovebis da SekumSvis koeficientebis gamoyenebiT.

14. Low Flow Bridge Hydraulics: Summarydabali dinebis xidebis hidravlika: Sejameba • Bridge piers are small obstruction to flow, friction losses predominate - Energy, Momentum, or WSPRO • xidebispirsebimciredabrkolebaadinebisTvis, Warbobsxaxunisdanakargi –energia, impulsi an WSPRO • Pier and friction losses predominate – Momentum • pirsi da xaxunisdanakargiWarbobs - impulsi • Flow passes through critical depth in vicinity of bridge - Energy or Momentum • dinebakveTskritikulsiRrmesxidismidamoebSi – energia an impulsi • Pier losses are dominant – Yarnell • pirsisdanakargiarisdominanti - iarneli • Supercritical flow without piers - Energy or Momentum • superkritikulidinebapirsebisgareSe – energia an impulsi • Supercritical flow with piers – Momentum • superkritikulidinebapirsebiT- impulsi

15. High Flow Bridge MethodsmaRali dinebis xidis meTodi • Energy Method - The area of the deck is subtracted and additional wetted perimeter is added. The water surface elevation represents the hydraulic grade line. • energiis meTodi – xidis savali nawili gamoiTvleba da damatebiTi sveli perimetri emateba. wylis zedapiris simaRle gviCvenebs hidravlikuri xarisxis xazs. • This method does not account for the shape of the entrance or piers. • es meTidi ar gamoiyeneba nakadis Serwymis moxazulobisTvis an pirsebisTvis • Conveyance is calculated treating the bridge as a cross section, including flow over the roadway. • gadazidvis gaangariSebisas xids ganvixilavT rogorc ganivi kveTs da moicavs dinebas gzatkecilis gadaRma.

16. High Flow Bridge MethodsmaRali dinebis xidis meTodi (2) Pressure and Weir Method - Treats the flow as two separate components. (2) wneva da jebiris meTodi – ganixilavs dinebas, rogorc ori gancalkevebuli komponents • Flow through the opening is pressure flow. • xidis Ria nawilis gaswvriv dineba aris Seviwroebuli (wnevis qveS myofi) • Gate equation • WiSkris gantoleba • Full pressure (Orifice) equation • sruli wnevis (naxvreti, Riobi) gantoleba • Weir equation for flow over the roadway, with submergence correction. • jebiris gantoleba gzis gadaRma, daZirvis SesworebebiT. Note: HECRAS will automatically select the appropriate pressure flow equation. SeniSvna: HECRASavtomaturadSearCevssworwnevisdinebisgantolebas

17. High Flow – PressuremaRali dineba - wneva

18. High Flow - Pressure (Sluice) FlowmaRali dineba – Seviwroebuli (Sluzebi) dineba Q = Total discharge through the bridge opening totaluri xarji xidis Ria nawilis gaswvriv Cd = Coefficient of discharge for pressure flow xarjis koeficienti Seviwroebuli dinebisTvis Abu = Net area of the bridge opening at section BU xidis Ria nawilis qselis zona BU seqciaSi Y3 = Hydraulic depth at section 3 hidravlikuri siRrme 3 seqciaSi Z = Vertical distance from maximum bridge low chord to the mean river bed elevation at section BU vertikaluri manZili xidis savali nawilis umdables horizontamde da ZiriTadi mdinaris kalapitis siRaRles Soris.

19. Coefficient of discharge for sluice gate flowxarjis koeficienti Sluzebiani gasasvlelis dinebisTvis

20. Possible evidence SesaZlebelimtkicebuleba High Flow – PressuremaRali dineba - wneva

21. High Flow - Pressure (Orifice) FlowmaRali dineba –Seviwroebuli dineba (naxvreti, Riobi) Used when both the upstream and downstream sides of the bridge is fully submerged gamoiyeneba, rodesac xidis orive, zedadinebis da qvedadinebis mxare sruliad aris daZiruli Q = Total discharge from full flowing orifice Riobidan gamavali wylis sruli xarjva C = Coeff. of discharge for fully submerged pressure flow sruliad daZiruli dinebis zewolis xarjis koeficienti H = The difference between the energy gradient elevation upstream & the water surface elevation downstream gansxvaveba energiis gradientisa da zedadinebis simaRles Soris & wylis zedapiris simaRle qvedadinebaSi A = Net area of the bridge opening xidis Ria nawilis qselis zona

22. High Flow - Pressure & WeirmaRali dineba – wneva da wyalgadasaSvebi jebiri

23. High Flow - Weir FlowmaRali dineba – wyalgadasaSvebi jebiris dineba • Q = Total flow over the weir • wyalgadasaSvebi jebiris sruli dineba • C = Coefficient of discharge for weir flow (~2.5 to 3.1 for free flow) • xarjis koeficienti wyalgadasaSvebi jebiris dinebisTvis (~2.5 - 3.1 Tavisufali dinebisTvis) • L = Effective length of the weir • wyalgadasaSvebis efeqturi sigrZe • H = Difference between energy elev. upstream and road crest • energiis simaRlis gansxvaveba zeadadinebasa da gzis kveTas Soris

24. High Flow – SubmergencemaRali dineba - daZirva daZiruli Semcirebis faqtori daZirva

25. High Flow – SubmergencemaRali dineba - daZirva

26. High Flow Bridge Modeling: SummarymaRali dinebis xidis modelireba: daskvna • When bridge deck is a small obstruction to the flow and not acting like a pressurized orifice, use energy method. • rodesac xidis savali nawili warmoadgens mcire winaaRmdegobas dinebisTvis da ar moqmedebs rogorc zewolis xvreli, umjobesia gamoviyenoT energiis meTodi • When overtopped and tailwater is not submerging flow, use pressure/weir method. • rodesac datborva da Camonadeni wyali ar uerTdeba dinebas, gamoviyenoT wnevis/wyalgadasaSvebi jebiris meTodi. • When overtopped and highly submerged, use energy method. • rodesac xdeba datborva da Zlieri daZirva, gamoviyenoT energiis meTodi

27. Adding the Bridgexidebis damateba

28. Locating Cross-Sections Near Bridgesganivi kveTebis ganlageba xidebTan

29. Equipotential lines: Lc is a distance from the bridge where the flowlines remain parallel to the main flow direction and there is no contraction. ekvipotenciurikonturebi: LcarismanZilixidisimnawilidan, sadacdinebiskonturirCebaparaleluriZiriTadidinebismimarTulebismimarT da araakumSvadi Locating Cross-Sections Near Bridgesganivi kveTebis ganlageba xidebTan

30. Locating Cross-Sections Near Bridgesganivi kveTebis ganlageba xidebTan Fully Effective Flow sruliad efeqturi dineba Fully Expanded Flow sruliad gafarTovebuli dineba Thru Bridge xidisgavliT Contraction SekumSva Expansion gafarToveba

31. Locating Cross-Sections Near Bridgesganivi kveTebis ganlageba xidebTan Le Lc Fully Effective Flow sruliad efeqturi dineba Fully Expanded Flow sruliad gafarTovebuli dineba 1 4 3 2 Lc and Le can be determined by field investigation during high flow or can be computed. Lc da Le SeiZleba ganvsazRvroT, rogorc savele kvleva maRali dinebis dros an SeiZleba gadaviTvaloT

32. 4 1 Locating Cross-Sections Near Bridgesganivi kveTebis ganlageba xidebTan The contraction and expansions are normally taken as linear in HECRAS gafarToveba da SekumSva HECRAS-Siganixileba rogorc wrfivi movlena 3 2

33. FC2= Froude number at section 2 ricxvi 2 seqciaSi FC1= same at section 1 igive 1 seqciaSi ExpansiongafarToveba

34. Qob: discharge conveyed at the two overbank sections (cfs). xarjior datborvisseqciaSi Q: total discharge in the section (cfs) totalurixarjiseqciaSi nob: Manning for the overbank sections maningiskoeficientiWalisseqciaSi nc: Manning for the channel. maningiskoeficientiarxisTvis ContractionSekumSva

35. 1 1 CR ER Contraction/Expansion RatioSekumSvis/gafarTovebis koeficienti Rule of Thumb: wesi: ER = 2:1 CR = 1:1

36. Contraction/expansion ratios - How do we use them?SekumSvis/gafarTovebis koeficienti - rogor viyenebT?

37. Given: mocemulia Fully expanded flow top width at Cross Section 1 = 300 feet sruliadgafarTovebulidinebaganivikveTismaqsimalurisigane 1 = 300 futi Fully expanded flow top width at Cross Section 4 = 250 feet sruliadgafarTovebulidinebaganivikveTismaqsimalurisigane 1 = 250 futi Distance from Point B to Point C (bridge opening width) = 40 feet distancia B wertilidan C wertilamde (xidisgaxsnilinawili) = 40 futi Find:Recommended locations of Cross Sections 1 and 4 ipoveT: ganivikveTisrekomendirebuliadgilmdebareoba 1 da 4 Le = 2 * (300 – 40) / 2 = 260 feet downstream of bridge Le = 2 * (300 – 40) / 2 = 260 futixididanqvedadinebisken Lc = 1 * (250 – 40) / 2 = 105 feet upstream of bridge Lc = 1 * (250 – 40) / 2 = 105 futixididanzedadinebisken Example Computation of Le and LcLe da Lc – s gadaTvlis magaliTebi This assumes ER=2 and CR=1 es uSvebs ER=2 da CR=1

38. Expansion & Contraction CoefficientsSekumSvis da gafarToebis koeficientebi

39. Expansion & Contraction CoefficientsSekumSvis da gafarToebis koeficientebi

40. Expansion and Contraction Example of Coefficients at Bridge XS’s SekumSva da gafarToveba koeficientebis magaliTebi xidebze Expansion/ gafarTovebaContraction/ kumSva Cross-Section 4 (furthest US) 0.5 0.3 ganivikveTi 4 (uSoresi “zd”) Cross-Section 3 0.5 0.3 ganivikveTi 3 Cross-Section 2 0.5 0.3 ganivikveTi 2 Cross-Section 1(furthest DS) 0.3 0.1 ganivikveTi1 (uSoresi “qd”) Use Cc = 0.3 0.3 0.3 0.1 Cc-sgamoyeneba Use Ce = 0.5 0.5 0.5 0.3 Ce-sgamoyeneba

41. Ineffective Flow Areasaraefeqturi dinebis are 2 3 1 4

42. Ineffective Flowsaraefeqturi dineba The ineffective area option is used at bridge sections 2&3 to keep all the active flow in the area of the bridge opening until the elevations associated with the left and/or right ineffective flow areas are exceeded by the computed water surface elevation!!! araefeqturi dinebis parametri gamoiyeneba 2 da 3 xidis seqciebSi, vinaidan xidis Ria nawilSi SevinarCunoT aqtiuri dinebis areali im momentamde, sanam gamoTvlili wylis zedapiris simaRle ar ascdeba marjvena an marcxena araefeqturi dinebis arealis simaRles. At XS’s 2 & 3

43. Ineffective Flow Areasaraefeqturi dinebis are Enter stations that represent the active flow area at the cross section daamateT saguSagoebi, romlebic asaxaven aqtiuri dinebis ares ganivi kveTebis seqciebSi. (Adjust lateral distance for bounding sections distance from bridge) (miusadageT lateraluri distancia raTa ganvsazRvroT sazRvrebi xidisTvis) Enter elevation that allows overbank areas to become effective when exceeded SeiyvaneT simaRlis maCveneblebi, romlebic datborvis areebis efeqtur dinebad gadayvanis saSualebas mogvcemen, rodesac wyali ascdeba sazRvars Rule of Thumb: wesi: XS-2 > Use elevation = (low chord + top of road)/2 for first estimate XS-2 > gamoiyeneT simaRle = (savali nawilis dabali horizonti + gzis zeda horizonti)/2 pirveli SefasebisTvis Assume ER=2:1 if flow can freely transition in out of bridge davuSvaT ER = 2:1 Tu dinebas SeuZlia Tavisuflad gadavides xidze Width should normally be as wide or wider than bridge opening sigane rogorc wesi unda iyos ufro didi, an xidis napralze ufro ganieri. XS-3 > Elevation should be set at top of road or slightly lower (0.1’-0.2’) simaRle unda mivuTiToT gzis zeda nawili an odnav dabali Assume a CR of 1:1 in the immediate vicinity of the bridge davuSvaT CR an 1:1 xidis uSualo siaxloves

44. Ineffective Flow Areasaraefeqturi dinebis are • Define Ineffective Flow Areas if Needed • Tu saWiroa gansazRvreT araefeqturi dinebis are • From Bridge data page or from XS Options (Select “Ineffective Flow Areas”) • xidebis monacemebis gverdidan an XS parametris gamoyenebiT (SearCieT araefeqturi dinebis are “Ineffective Flow Areas”)

45. Bridge Dataxidebis monacemebi A word file has been developed to assist in organizing the data at bridges: vordis faili iyo SemuSavebuli raTa daxmareba gaewia xidebTan dakavSirebuli monacemebis organizaciaSi: es ar mitargmnia. vTargmno?

46. Bridge Dataxidebis monacemebi A word file has been developed to assist in organizing the data at bridges/culverts: vordis faili iyo SemuSavebuli raTa daxmareba gaewia xidebTan dakavSirebuli monacemebis organizaciaSi: es ar mitargmnia. vTargmno?

47. Graphic to assist in visualizing the data at bridges:grafika xidebis vizualizaciis xelSewyoba gawvdomisSekumSva gawvdomisgafarToveba dinebis gadaadgilebis idealuri mrudi 1D modelirebisTvis

48. Q: How would the flow expand below these bridges? kiTxva: rogorvrceldebadinebaxidisqveS?

49. Select the Brdg/Culv button from the geometry data window: SearCieT“Brdg/Culv” Rilakigeometriulimonacemebisfanjridan Adding the Bridgexidis damateba

50. This brings up the Bridge Culvert Data window: risSedegadacgamoCndebaxidiswyalsadenismonacemTafanjara Adding the Bridgexidis damateba