Design of Trash Rack
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Transcript of Design of Trash Rack
Design of Semi Circular Intake Supporting Structure1 Bellmounth Opening & Transition
a) Size of OpeningSlope 1 in 99.00 0.010101Angle of center line of HRT with horizontal Ø 0.01 rad
Co-eff of Contraction 0.6 as per IS 9761 Cl.5.1.2
Design Discharge Q 240 cumec
Dia of HRT (in org proposal D shaped has been provided) D 8.5
C/s Area of HRT 65.38625
Opening Area of Bellmouth 108.982643 TanØ
Upper Nappe Height 6.63135204 m 0.000102
Lower Nappe Height 6.7304541 m
Height of Bell Mouth 13.3618061 m
Width of Bell Mouth 8.15628078 m Profile of Bell mouth & Entry details has to be followed as per IS 9761 Cl 5.1
Velocity through Bellmouth 2.20218554 m/secMinimum Submergence for avoiding vortex
Froude Number 0.24116259limiting value 0.333333331to1.5 times the intake ht 1.819
Case-1 Submergence ht 10.2 m taking 1.2 11.65182Case-2 Using formula h 8.34976404 m Case-3 Submergence ht from IS 9761 Cl.4.2.1 © h 10.6894449 m
taking max value of three cases 10.6894449 mBottom level of HRT 2193 mBase level of Trash Rack 2192 mMDDL required 2207.93944 m say 2208.00 m
2 Trash Rack hydraulic designTrash Bar Design
Radius for semi circular intake structure 9.32099768 m say 10.00 mPerimeter of the trash rack 31.4159265
Assuming normal velocity through trash rack 1.5 m/sec
Considering hand raking, velocity through trash rack 0.75 m/sec as per IS 9761 Cl.5.3.6
Area of waterway required 320 m2Distance between MDDL to Bottom of HRT 15.00 mHeight of trash rack 16.00 m 22.2849
Assuming Trash rack panel width 4.00 m 44.5698
Assuming Trash rack panel height 4.00 m
Thickness of Trash bar 10.00 mm as per IS 11388 Cl.8.5.1
Spacing of Trash Bar 100.00 mm as per IS 11388 Cl.8.4 limit 40-100 mm
The depth of Trash Bar 50 mm as per IS 11388 Cl.8.5 Unsupported length limiting value as per code IS11388 700.00 mm
Provided Unsupported length 500.00 mm
Differential head acting on trash rack 6.00 mUDL load on trash Bar w 60.00 kg/mMaximum Bending moment BM 18.75 N-m
Yield stress 250.00 N/mm2Failure Stress 116.25 N/mm2Safe stress 76.73 N/mm2
244.38 mm3Zprov 4166.67 mm3Actual Stress 4.50 N/mm2Hence Zprov > Zreq Trash Bar Safe Design
Cc
Ahrt M2
M2
h1
h2
he =(h1+h2)
be
Vbellmouth
Fr
R=1.1428be
Vnt
Vt
Anet
TRPw
TRPh
TBt
TBs
TBd
TBl
hd
fy
Zreq
2 1/2 11 2
0.7912
(1.21tan 0.0847) 1.1tan
0.077 tan
Cos
Cos
h D
h D
INTERMIDIATE ISJC 150 Channel Design Section PropertiesWidth of ISJC 150 flange 45.00 mmUdl on ISMC channel 270.00 kg/mMaximum bending moment 5400.00 N-mYield stress fy 250.00 N/mm2Permissible bending stress σ 165.00 N/mm2Zreq 32727.27 mm3Z about xx axis for ISJC150 from Sp 6 -1 62800.00 mm3Hence Zprov > Zreq Intermidiate ISJC 150 Safe Design 85.98726
Clear Area for Water WayNos of Intermidiate IMJC 150 horizontal members 9.00 nos 9.00 nosArea of IMJC 150 1620000.00 mm2Nos of Trash Bars 41.00 nos 41.00 nosArea of Trash Bars 20500.00 mm2Total restricted area 1640500.00 mm2 1.6405 m2Whole area 16.00 m2Clear Area for Water Way 14.36 m2Area req 160.00 m2Nos of panel 11.14 nos 12.00 nosconsidering 50% chocking nos of Panel 24.00 nosTotal area 344.63Velocity 0.70if hand raking Velocity should be less than 0.75m/s, hence its OKif mechanical raking velocity ~ 1.5 m/s its not desirable
Angle between adjacent piers 30.00 degreeNos of bay 6.00 nosNos of row available upto MDDL 4.00 nosNos of row required 4.00 nosSafe Arrangement of Trash Rack
Semi-Circular Slabthickness of slab 0.20 mtotal weight of semi circular slab 785.40 KNas semi circular slab acts as a one way slab, load on curve beam 392.70 KNlength of curved beam 31.42 mUdl load on beam 12.50 KN/m
Design of Semi Circular Intake Supporting Structure1 Bellmounth Opening & Transition
a) Size of OpeningSlope 1 in 99.00Angle of center line of HRT with horizontal Ø 0.01 rad
Co-eff of Contraction 0.6 as per IS 9761 Cl.5.1.2Design Discharge Q 240 cumec
Dia of HRT (in org proposal D shaped has been provided) D 8.5
C/s Area of HRT 65.38625
Opening Area of Bellmouth 108.982643
Upper Nappe Height 6.63135204 m
Lower Nappe Height 6.7304541 m
Height of Bell Mouth 13.3618061 m
Width of Bell Mouth 8.15628078 mProfile of Bell mouth & Entry details has to be followed as per IS 9761 Cl 5.1
Velocity through Bellmouth 2.20218554 m/secMinimum Submergence for avoiding vortex
Froude Number 0.24116259limiting value 0.333333331to1.5 times the intake ht
Case-1 Submergence ht 10.2 mCase-2 Using formula h 8.34976404 m Case-3 Submergence ht from IS 9761 Cl.4.2.1 © h 10.6894449 m
taking max value of three cases 10.6894449 mBottom level of HRT 2193 mBase level of Trash Rack 2192 mMDDL required 2207.93944 m
2 Trash Rack hydraulic designTrash Bar Design
Width between center line of piers R=1.42857b 12.142845 m
Perimeter of the trash rack 40.8407045
Assuming normal velocity through trash rack 1.5 m/sec
Considering hand raking, velocity through trash rack 0.75 m/sec
Area of waterway required 320 m2Distance between MDDL to Bottom of HRT 15.00 m
Cc
Ahrt M2
M2
h1
h2
he =(h1+h2)
be
Vbellmouth
Fr
Vnt
Vt
Anet
2 1/2 11 2
0.7912
(1.21tan 0.0847) 1.1tan
0.077 tan
Cos
Cos
h D
h D
Height of trash rack 16.00 m
Assuming Trash rack panel width 4.00 m
Assuming Trash rack panel height 3.60 m
Thickness of Trash bar 10.00 mm
Spacing of Trash Bar 100.00 mm
The depth of Trash Bar 50 mmUnsupported length limiting value as per code IS11388 700.00 mm
Provided Unsupported length 500.00 mm
Differential head acting on trash rack 6.00 mUDL load on trash Bar w 0.60 KN/mMaximum Bending moment BM 18.75 N-m
Yield stress 250.00 N/mm2Failure Stress 116.25 N/mm2Safe stress 76.73 N/mm2
244.38 mm3Zprov 4166.67 mm3Actual Stress 4.50 N/mm2Hence Zprov > Zreq Trash Bar Safe Design
INTERMIDIATE ISMC 150 Channel Design Section PropertiesWidth of ISJC 150 flange 45.00 mmUdl on ISMC channel 2.70 KN/mMaximum bending moment 5400.00 N-mYield stress fy 250.00 N/mm2Permissible bending stress σ 165.00 N/mm2Zreq 32727.27 mm3Z about xx axis for ISJC150 from Sp 6 -1 62800.00 mm3Hence Zprov > Zreq Intermidiate ISJC 150 Safe Design
Clear Area for Water WayNos of Intermidiate IMJC 150 horizontal members 8.20 nosArea of IMJC 150 1620000.00 mm2Nos of Trash Bars 41.00 nosArea of Trash Bars 205000.00 mm2Total restricted area 1825000.00 mm2Whole area 14.40 m2Clear Area for Water Way 12.58 m2For mechanical rakingArea req for mechanical raking 160.00 m2Nos of panel 12.72 nosconsidering 50% chocking nos of Panel 26.00 nosTotal area 326.95 m/s
TRPw
TRPh
TBt
TBs
TBd
TBl
hd
fy
Zreq
Velocity 0.73 m/s
For manual rakingArea req for manual raking 320.00 m2Nos of panel 25.45 nosconsidering 50% chocking nos of Panel 52.00 nosTotal area 653.90 m2Velocity 0.37 m/s
if hand raking Velocity should be less than 0.75m/s, hence its OKif mechanical raking velocity ~ 1.5 m/s its not desirable
Angle between adjacent piers 30.00 degreeNos of bay 6.00 nosNos of row available upto MDDL 4.44 nosNos of row required 4.33 nosSafe Arrangement of Trash Rack
Semi-Circular Slabthickness of slab 0.20 mtotal weight of semi circular slab 1327.32 KNas semi circular slab acts as a one way slab, load on curve beam 663.66 KNlength of curved beam 40.84 mUdl load on beam 16.25 KN/m
0.010101
as per IS 9761 Cl.5.1.2
TanØ
0.000102 0.000123 0.084823 0.291245 0.500026 0.79127 0.011111
0.79104
1.819taking 1.2 12.14285
say 2208.00 m11.65182
say 13.00 m
as per IS 9761 Cl.5.3.6
25.44732
50.89463
as per IS 11388 Cl.8.5.1
as per IS 11388 Cl.8.4 limit 40-100 mm
as per IS 11388 Cl.8.5
85.98726
9.00 nos
41.00 nos
1.825 m2
13.00 nos
26.005 10.4
10.68944
3.125
0.780159 6.631352
0.000778 0.791818 6.730454