HECRAS Bridges
HECRAS xidebi
by G. Parodi
WRS – ITC – The Netherlands
g. parodi
WRS-ITC- niderlandebi
ITC Faculty of Geo-Information Science and Earth Observation of the University of Twente
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
4
3
2
1
2 Types of Flow at Bridges
xidis dinebis 2 tipi


Low Flow - Flow where the water surface does not reach the low beam
dabali dineba - dineba, sadac wylis zedapiri ar aRwevs xidis koWs


High Flow - Flow where the water surface reaches the deck or higher
maRali dineba - dineba, sadac wylis zedapiri aRwevs an cdeba xidis saval nawils
Q: Is this low flow or high flow?
kiTxva: es dabali dinebaa Tu maRali?
Low Flow
dabali dineba
Low Flow Bridge Modeling: 3 Types of Flow
dabali dinebis xidis modelireba: dinebis 3 tipi
A klasi, susti dineba -subkritikuli
dineba
• energia, impulsi, iarneli da aSSwr (WSPRO)
B klasi, susti dineba – dineba
romelic scdeba kritikul siRrmes
• energia da impulsi
B klasi, susti dineba –
superkritikuli dineba
• energia da impulsi
Class A Low Flow - Subcritical
Flow
• Energy, Momentum, Yarnell, and WSPRO
Class B Low Flow - Flow
passes through critical depth
• Energy and Momentum
Class C Low Flow Supercritical Flow
• Energy and Momentum
Low Flow Bridge Hydraulics: 4 methods of modeling
dabal 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.
Low Flow Bridge Modeling
Class A Low Flow - Energy Method
dabal dinebiani xidis modelireba
A klasi dabali dineba – energiis meTodi

Friction losses are computed as length times average friction slope.

xaxunis danakargis gaangariSeba xdeba rogorc sigrZe ayvanili saSualo xaxunis kuTxis xarisxSi.

Energy losses are empirical coefficient times change in velocity head (expansion
and contraction losses).

energiis danakargi aris empirikuli koeficienti ayvanili siCqaris maqsimumis xarisxSi (gafarTovebis
da SekumSvis danakargi)

Does not account for pier drag forces.

ar xdeba pirsebs damuxruWebis Zalis gaTvaliswineba
Low Flow Bridge Modeling
Class A Low Flow - Momentum Method
dabal dinebiani xidis modelireba
A klasi dabali dineba – impulsis meTodi

Friction losses are external skin friction = wetted perimeter times
length times shear stress.

xaxunis danakargi aris gare xaxuni = sveli perimetri ayvanili sigrZis xarisxSi da ayvanili
gadanacvlebis daZabulobis xarisxSi

Requires entering coefficient of drag for piers, CD

moiTxovs pirsebis damuxruWebis koeficientis damatebas
Low Flow Bridge Modeling
CD Coefficients for Piers

Circular Pier
1.20

Elongated piers with semi circular ends (wagrZelebuli pirsi semiwriuli boloTi)

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

Triangular nose with 30 degree angle (triangularuli xmauri 30 gradusiani kutxiT)

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)
(wriuli pirsi)
1.33
2.00
(marTkuTxa xmauriani pirsi)
1.00
1.72
Low Flow Bridge Modeling
Class A Low Flow - Yarnell Equation
dabali dinebis xidis modelireba
A 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
Low Flow Bridge Modeling
Yarnell’s Pier Coefficient, K
dabali dinebis xidebis modelireba
iarnelis pirsis koeficienti K

Semi-circular nose and tail

semi-cirkularuli xmauri da kudi

Twin-cylinder piers with connecting diaphrag

ormagi cilindruli pirsi dakavSirebuli diafragmiT

Twin-cylinder piers without diaphragm

ormagi cilindruli pirsi diafragmis gareSe

90 degree triangular nose and tail

90 gradusiani triangularuli xmauri da kudi

Square nose and tail

marTkuTxa xmauri da kudi

Ten pile trestle bent

aTi gaerTianebuli sayrdeni
0.90
0.95
1.05
1.05
1.25
2.50
Low Flow Bridge Modeling
Class A Low Flow – WSPRO
dabali dinebis xidis modelireba
A klasi dabali dineba - WSPRO
 Federal Highway Administrations method of analyzing
bridges
 federaluri gzatkecilis xidebis analizis administratoruli meTodi
 Uses energy equation in an iterative procedure
 gamoviyenoT energiis gantoleba iteraciuli (ganmeorebiTi) procedurebisTvis
Class B and C Low-flow Methods
B da C klasi- dabali dineba

Two methods available:

ori meTodia xelmisawvdomi:
1.
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.
2.
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.
3.
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.
4.
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.
Low Flow Bridge Hydraulics: Summary
dabali dinebis xidebis hidravlika: Sejameba

Bridge piers are small obstruction to flow, friction losses predominate - Energy,
Momentum, or WSPRO

xidebis pirsebi mcire dabrkolebaa dinebisTvis, Warbobs xaxunis danakargi –energia, impulsi an WSPRO

Pier and friction losses predominate – Momentum

pirsi da xaxunis danakargi Warbobs - impulsi

Flow passes through critical depth in vicinity of bridge - Energy or Momentum

dineba kveTs kritikul siRrmes xidis midamoebSi – energia an impulsi

Pier losses are dominant – Yarnell

pirsis danakargi aris dominanti - iarneli

Supercritical flow without piers - Energy or Momentum

superkritikuli dineba pirsebis gareSe – energia an impulsi

Supercritical flow with piers – Momentum

superkritikuli dineba pirsebiT - impulsi
High Flow Bridge Methods
maRali dinebis xidis meTodi
(1) Energy Method - The area of the deck is subtracted and additional wetted perimeter is added. The water
surface elevation represents the hydraulic grade line.
(2)
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.
High Flow Bridge Methods
maRali 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: HECRAS avtomaturad SearCevs swor wnevis dinebis gantolebas
High Flow – Pressure
maRali dineba - wneva
High Flow - Pressure (Sluice) Flow
maRali dineba – Seviwroebuli (Sluzebi) dineba

3V32 

Z
Q  Cd  Abu Y3 - 
2 2 g 

1
2
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.
Coefficient of discharge for sluice gate flow
xarjis koeficienti Sluzebiani gasasvlelis dinebisTvis
High Flow – Pressure
maRali dineba - wneva
Possible evidence
SesaZlebeli mtkicebuleba
High Flow - Pressure (Orifice) Flow
maRali 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  C A 2gH
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
High Flow - Pressure & Weir
maRali dineba – wneva da wyalgadasaSvebi jebiri
High Flow - Weir Flow
maRali dineba – wyalgadasaSvebi jebiris dineba
3
Q  CLH
2

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
High Flow – Submergence
maRali dineba - daZirva
Qsubmerged  Qf ree  Reduction Factor
H2
Submergenc e 
H1
daZirva
daZiruli Semcirebis faqtori
High Flow – Submergence
maRali dineba - daZirva
High Flow Bridge Modeling: Summary
maRali 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
Adding the Bridge
xidebis damateba
Locating Cross-Sections Near Bridges
ganivi kveTebis ganlageba xidebTan
Locating Cross-Sections Near Bridges
ganivi kveTebis ganlageba xidebTan
 Equipotential lines: Lc is a distance from the bridge where the
flowlines remain parallel to the main flow direction and there is
no contraction.

ekvipotenciuri konturebi: Lc aris manZili xidis im nawilidan, sadac dinebis konturi rCeba paraleluri ZiriTadi
dinebis mimarTulebis mimarT da araa kumSvadi
Locating Cross-Sections Near Bridges
ganivi kveTebis ganlageba xidebTan
Fully
Effective
Flow
sruliad efeqturi dineba
Contraction
SekumSva
Thru Bridge
xidis gavliT
Expansion
gafarToveba
Fully
Expanded
Flow
sruliad gafarTovebuli
dineba
Locating Cross-Sections Near Bridges
ganivi kveTebis ganlageba xidebTan
Le
Lc
Fully
Effective
Flow
sruliad efeqturi
dineba
Fully
Expanded
Flow
sruliad
gafarTovebuli
dineba
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
1
Locating Cross-Sections Near Bridges
ganivi kveTebis ganlageba xidebTan
4
3
2
The contraction and expansions are
normally taken as linear in HECRAS
gafarToveba da SekumSva HECRAS-Si
ganixileba rogorc1 wrfivi movlena
Expansion
gafarToveba
 Fc2 
  1.8 105 Q
ER  0.421  0.485
 Fc1 
 FC2= Froude number at section 2
 FC1= same at section 1 igive 1 seqciaSi
ricxvi 2 seqciaSi
Contraction
SekumSva
 Fc2 
 nob 
 Qob 
  1.86

CR  1.4  0.333
  0.19
 Q 
 Fc1 
 nc 
2


Qob: discharge conveyed at the two overbank sections (cfs).
xarji or datborvis seqciaSi


Q: total discharge in the section (cfs)
totaluri xarji seqciaSi


nob: Manning for the overbank sections
maningis koeficienti Walis seqciaSi


nc: Manning for the channel.
maningis koeficienti arxisTvis
0.5
Contraction/Expansion Ratio
SekumSvis/gafarTovebis koeficienti
Rule of Thumb:
wesi:
ER = 2:1
CR = 1:1
1
CR
1
ER
Contraction/expansion ratios - How do we use them?
SekumSvis/gafarTovebis koeficienti - rogor viyenebT?
Example Computation of Le and Lc
Le da Lc – s gadaTvlis magaliTebi

Given:

mocemulia

Fully expanded flow top width at Cross Section 1 = 300 feet

sruliad gafarTovebuli dineba ganivi kveTis maqsimaluri sigane 1 = 300 futi

Fully expanded flow top width at Cross Section 4 = 250 feet

sruliad gafarTovebuli dineba ganivi kveTis maqsimaluri sigane 1 = 250 futi

Distance from Point B to Point C (bridge opening width) = 40 feet

distancia B wertilidan C wertilamde (xidis gaxsnili nawili) = 40 futi

Find: Recommended locations of Cross Sections 1 and 4

ipoveT: ganivi kveTis rekomendirebuli adgilmdebareoba 1 da 4

Le = 2 * (300 – 40) / 2 = 260 feet downstream of bridge

Le = 2 * (300 – 40) / 2 = 260 futi xididan qvedadinebisken

Lc = 1 * (250 – 40) / 2 = 105 feet upstream of bridge

Lc = 1 * (250 – 40) / 2 = 105 futi xididan zedadinebisken
This assumes ER=2 and CR=1
es uSvebs ER=2 da CR=1
Expansion & Contraction Coefficients
SekumSvis da gafarToebis koeficientebi
Expansion & Contraction Coefficients
SekumSvis da gafarToebis koeficientebi
Contraction Expansion
No Transition
0
0
Gradual Transition
0.1
0.3
Typical Bridge Transition
0.3
0.5
Abrupt Transition
0.6
0.8
kumSva
gafarToveba
araa gadasvla
0
0
TandaTanobiTi gadasvla
0.1
0.3
tipiuri xidis gadasvla
0.3
0.5
uecari gadasvla
0.6
0.8
Expansion and Contraction
Example of Coefficients at Bridge XS’s
SekumSva da gafarToveba
koeficientebis magaliTebi xidebze
Expansion/ gafarToveba
Cross-Section 4 (furthest US)
Contraction/ kumSva
0.5
0.3
Cross-Section 3
ganivi kveTi 3
0.5
0.3
Cross-Section 2
ganivi kveTi 2
0.5
0.3
Cross-Section 1(furthest DS)
ganivi kveTi 1 (uSoresi “qd”)
0.3
0.1
ganivi kveTi 4 (uSoresi “zd”)
Use Cc = 0.3
Cc-s gamoyeneba
0.3
0.3
0.1
Use Ce = 0.5
0.5
0.5
0.3
Ce-s gamoyeneba
Ineffective Flow Areas
araefeqturi dinebis are
4
3
2
1
Ineffective Flows
araefeqturi 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
Ineffective Flow Areas
araefeqturi 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
Ineffective Flow Areas
araefeqturi 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”)
Bridge Data
xidebis 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?
Bridge Data
xidebis 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?
Graphic to assist in visualizing the data at bridges:
grafika xidebis vizualizaciis xelSewyoba
gawvdomis SekumSva
gawvdomis gafarToveba
dinebis gadaadgilebis idealuri mrudi 1D
modelirebisTvis
Q: How would the flow expand below
these bridges?
kiTxva: rogor vrceldeba dineba xidis qveS?
Adding the Bridge
xidis damateba
 Select the Brdg/Culv button from the geometry data window:
 SearCieT “Brdg/Culv” Rilaki geometriuli monacemebis fanjridan
Adding the Bridge
xidis damateba


This brings up the Bridge Culvert Data window:
ris Sedegadac gamoCndeba xidis wyalsadenis monacemTa fanjara
Adding the Bridge
xidis damateba
There are several other options in the options menu from the bridge data window as well as the view menu
xidebis monacemebis fanjaraSi, parametrebis meniuSi, arsebobs ramodenime sxva brZaneba iseve, rogorc gamoxazvis meniuSi
Adding the Bridge
xidis damateba
From the options
menu, select “Add
a Bridge and/or
Culvert”:
opciebis meniudan
SearCieT “daamateT xidi
an/da wyalsadeni “Add
a Bridge and/or
Culvert”
Adding the Bridge
xidis damateba


This brings up a window with the adjacent upstream and downstream crosssections plotted:
Sedegad gamoCndeba fanjara zedadinebis da qvedadinebis ganivi kveTebis damatebiTi naxazebiT:
Deck/ Roadway
xidis savali nawili/zatkecili


Next, select the Deck/Roadway button from the Bridge data window:
Semdeg SearCieT xidis savali nawili/gzatkecili-s Rilaki xidebis monacemTa fanjaraSi
Deck/Roadway
xidis savali nawili/gzatkecili
Notice the weir
coefficient and max
submergence
window are showing
the default values:
aRsaniSnavia, rom winaswaraa
gansazRvruli jebiris koeficienti da
maqsimaluri CaZirvis koeficienti:
Deck/Roadway
xidis savali nawili/gzatkecili
Enter the data for the
required values. Note
that the U.S. and D.S.
sideslopes (SS) are for
cosmetic purposes
only*
SeiyvaneT monacemebi savaldebulo
sidideebis aRsawerad. aRsaniSnavia, rom
“z.d” da “q.d” gamoiyeneba mxolod
kosmetikuri funqciisTvis
*unless using the WSPRO method for low flow
Tu araa miTiTebuli WSPRO meTodi dabali dinebisTvis
Deck/Roadway
xidis savali nawili/gzatkecili
Use the “Copy Up to Down”
button to repeat the stationhigh chord-low chord data
from the upstream to the
downstream side, if
applicable:
gamoiyeneT “Copy Up to Down”
Rilakebi, raTa ganmeorebiT SeviyvanoT
saguSagos-simaRle, savali nawilis qveda
horizontis monacemebi zedadinebidan
qveda dinebisken, im SemTxvevaSi Tu
monacemebi Sesaferisia.
Deck/Roadway
xidis savali nawili/gzatkecili
After selecting OK from the
bridge deck window, it
replots the U.S. and D.S. xsections showing the bridge
deck:
mas Semdeg rac, xidis savali nawilis
fanjaraSi SerCeuli iyo Tanxmobis
Rilaki “OK”, is asaxavs xidis saval
nawils “qd” da “zd” X seqciaSi
Deck/Roadway
xidis savali nawili/gzatkecili
 Q: What is the extent of the
bridge deck on these bridges?
 kiTxva: ra gavrcoba aqvT saval nawilebs am
xidebze?
Deck/Roadway
xidis savali nawili/gzatkecili
 Q: What is the extent of
the bridge deck on these
bridges?
 kiTxva: ra gavrcoba aqvT saval
nawilebs am xidebze?
Piers
pirsi

Piers can be added by selecting the Pier button from the bridge data window:

pirsis damateba SesaZlebelia, Tu avirCevT pirsis Rilaks xidebis monacemebis fanjridan
Piers
pirsi
This brings up the Pier Data
Editor where you can add the
data for the pier(s) :
es gvaZlevs pirsis monacemebis redaqtirebis
saSualebas, da SesaZlebelia monacemebis
damateba pirsebisTvis:
Use the “Copy Up to Down”
button, if applicable:
gamoiyeneT “Copy Up to
Down” Rilaki, Tu saWiroa
Piers
pirsi
The pier is then
shown graphically
on the plot:
pirsi Semdgom gamoisaxeba
grafikulad naxazze
Bridge Modeling Approach
xidis modelirebis midgoma


The modeling options, including low flow and high flow modeling methods, are available by
selecting the Bridge Modeling Approach button:
modelirebis opcia, romelic moicavs dabali dinebis da maRali dinebis modelirebas xelmisawvdomia Tu avirCevT xidis
modelirebis midgomis Rilaks
Bridge Modeling Approach
xidis modelirebis midgoma
This brings up Bridge Modeling
Approach Editor window.
Notice the option to compute
each type of low flow method
and the option to select which
one you use:
es gviCvenebs xidis modelirebis midgomis
redaqtoris fanjaras. aRsaniSnavia
parametri, romelic iTvlis dabali dinebis
yvela tipis meTodiT da parametri romelic
saSualebas gvaZlevs avirCioT dinebis tipi:
Q: Is using highest energy always a good idea?
kiTxva: ramdenad gamarTlebulia umaRlesi energiis gamoyeneba?
Bridge Modeling Approach
xidis modelirebis midgoma
Orifice Coef. between 0.7 and 0.9
SesarTavis koeficienti
0.7 sa da 0.9 s Soris
Bridge Modeling Approach
xidis modelirebis midgoma
Note the:
gaiTvaliswineT:
Bridge Modeling Approach
xidis modelirebis midgoma
Click on it to get a table of values
daaklikeT, raTa miiRoT sidideebis cxrili
Unique Bridge Problems
gansxvavebuli xidis problemebi
 Debris
 namsxvrevebi
 Parallel Bridges
 paraleluri xidebi
 Bridges on a Skew
 xidebi mosaxvevSi
 Examples
 magaliTebi
Debris
naleqebi

What about debris?

naleqebis Sesaxeb

Check “Floating Debris” on pier data editor

SeamowmeT “motivtive naleqebi” pirsis monacemTa
editorSi

Enter rectangular dimensions

daumateT marTkuTxa mimarTuleba
Debris
namsxvrevebi
•On pier
•pirsze
•Solid
•myari
•Floats
•motivtive
Parallel Bridges
paraleluri xidebi

If very close could be modeled as one, OR
two linked with 1 Cross Section

Tu axlosaa erTmaneTTan modelSi Segvyavs, rogorc erTi xidi an
ganvixilavT, rogorc or, magram erT prfilTan dakavSirebul xidad.

If flow expands between, add sections to
model transition.

Tu dineba afarToebs xidebs Soris arsebul sivrces, maSin
daamateT seqcia Sualeduri gadasvlis modelirebisTvis.
Two bridges do not necessarily have twice the loss
Bridges on a Skew
xidebi da moRunva
Flow
WB
Wp

L
b


Skew increases pier width & decreases bridge opening
moRunva adidebs pirsis siganes da amcirebs xidis Ria nawils.


Bridge skew up to 20o show no additional flow problems
xidis 20 * mde gadaRunvis dros Tavs ar iCenen damatebiTi probelebi.


Projected width of bridge based on cosine of skew angle
xidis kosinusis daxris kuTxeze damyarebuli proeqcirebuli sigane
Use Skew Bridge/Culvert option on bridge/culvert editor
moRunuli xidis/ milebis opciebi xidis/ wyalsadenis editorSi
Warning: Review Carefully!
gafrTxileba: gadaxedeT yuradRebiT
Q: What are the
modeling issues?
kiTxva: ra aris modelirebis
daniSnuleba?
Q: What are the
modeling issues?
kiTxva: ra aris modelirebis
ZiriTadi mizani?
Q: What aspects of these bridges do
you need to model in HECRAS?
kiTxva: am xidebis romeli aspeqtebis
gaTvaliswinebaa saWiro modelirebisas?
Q: What aspects of these bridges do
you need to model in HECRAS?
kiTxva: am xidebis romeli aspeqtebis
gaTvaliswinebaa saWiro HECRAS –Si
modelirebisas?