trfrfdn-20 mva(runnisaidpur)

20MVA Transf fdn

CLIENT POWER GRID CORPORATION OF INDIA LIMITED SHYAMA POWER (I) LTDPROJECT BIHAR SUB TRANSMISSION SYSTEM, PHASE II, PART II DESIGN NO.- 1000SUBSTATION 132/33kV Runnisaidpur S/S

Design of Transformer Foundation

Transformer Detail

Equipment Type : 20 MVA(3 Phase)Length, L 5.9 mWidth, B 3.2 mHeight from PL, H 4.5 mWeight, W 50850 Kgs

Ref drg no. EM10/D10401 (R-1) - GA of 20MVA Transformerof EMCO Ltd.

General inputs :Basic wind Speed, Vb 47 m/sRisk coefficient, k1 1.07Terrain ht & str size factor, k2 1.00Topogrphy factor, k3 1.00Design wind speed, Vz 50.29 m/sDesign wind pressure, Pz 1.517 KN/m2Seismic Zone 4Zero period acceleration value , Z 0.24

2.5g

Importance factor , I 1.5Response Reduction factor , R 3Damping 5%Ah 0.15

(R/I)

Base Shear, Vb = Ah x W 7627.50 KgsNet safe Bearing capacity 68.67 KN/m2 =7*9.81Bulk density of soil, n 18.39 KN/m3 =1.875*9.81

0Cohesion, C 34.34 KN/m2 =3.5*9.81Depth of water table 4.5 mself wt of grating 70 Kg/m2Live load on grating 300 kg/m2Thickness of gravel topping over grating 0.1 mwt of gravel topping 240 Kg/m2Partial factor of safety 2.2

Spectral acceleration coeffient for soil , Sa

= (Z/2)* (Sa/g)

Angle of repose, f 0

20MVA Transf fdn


1. Design of Transformer main Block

Size of transformer mass block 2.35 m x 3.15 m

300

2000 1700

300

500 2350 5003350

Horizontal Force due to Wind, 40.29 KN =1.52 x 5.9 x 4.5

Add 20% for projections 48.35 KNMoment at PL, Mw 108.78 KN-m =48.35 x 4.5/2

Horiz. Force due to Seismic Load, 74.83 KN =7627.5 x 9.81/1000

Moment at PL, Ms 168.36 KN-m =74.83 x 4.5/2

Design Loads at Plinth LevelVertical Equipment Load 498.84 KN =50850 x 9.81/1000

Horizontal Shear 74.83 KNMoment 168.36 KN-m

Transformer Block300

Wall

3150 2300 1700

500

300150

400 5250 4350 400150

4150

When clear gap between wall and main block exceeds 2.0m, provide grating support column at a distance of 2.0 m from main block,Grating Area = 13.88 m2 =(5.25+4.35-3.15)/2x2.35+2.0x3.15

Grating Load due to dead weight 971.51 Kg = 70 x 13.88

20MVA Transf fdn


Load due to gravel topping 3330.90 Kg = 240 x 13.88

20MVA Transf fdn


Combined concentric Load 42.21 KN = (971.51 + 3330.9) x 9.81/1000

Load due to live load on grating 40.85 KN = 300 x 13.88 x 9.81/1000

Total wt due to Grating and others 83.05 KN

Check for Bearing pressure

Area of fdn 13.90 m2 = 4.15 x 3.35

Moment of Inertia, I 13.00 m4 = 4.15 x 3.35^3/12

or, Zyy = 7.76 m3 = 13/(3.35/2)

Weight of concrete(fdn only) 474.39 KN= (((1.7x25) + 0.3x25)x 3.15 x 2.35)+(3.35 x 4.15 x 0.3 x25)

Load combinations: 1) DL 1056.28 KN =498.84 + 474.39 + 83.05

2) DL+moment DL 1056.28 KN =498.84 + 474.39 + 83.05

Moment 340.46 KN-m = 74.83 x (4.5 /2 + 2.3 )

SBC at toe level 85.84 KN/m2 = ( 68.67 x 1.25 )

Pressure due overburden soil 36.79 KN/m2 = 2 x 18.39

Bearing pressure developed incase 1: 39.19 KN/m2 = 1056.28 / 13.9 - 36.79

39.19 < 68.67 Hence Okcase 2: 83.05 KN/m2

= 1056.28 / 13.9 + 340.46 / 7.76 - 36.79

83.05 < 85.84 Hence Ok

Check for Overturning

Weight of concretea) Pedestal 370.13 KN = 2 x 2.35 x 3.15 x 25

b) Raft 104.27 KN = 3.35 x 4.15 x 0.3 x 25

Total vertical load 973.23 KN = 370.13 + 104.27 + 498.84

Restoring moment about toe of fdn 1467.15 KN-m = 0.9 x 973.23 x 1.675

Overturning moment 340.46 KN-m

F.O.S. against Overturning 4.31 > 2.2 Hence O.K.

Check against sliding

Maximum horizontal shear 74.83 KNCohesion, c = 34.34 KN/m2Coefficient of pressure = 1.00 = tan^2(45 + 0/ 2) Deg.

Resisting passive pressure, P = 105.46 KN/m2 = 2 x 34.34 x 1 + 18.39 x 2 x 1

Minimum area = 5.00 m2 = 2.35 x 1.7 + 3.35 x 0.3

Max. frictional resistance = 527.29 KN = 105.46 x 5

F.O.S. against Sliding = 7.05 = 527.29 / 74.83

> 2.2, Hence O.K.

REINFORCEMENT FOR BLOCK FOUNDATION ABOVE PAD

Provide Vertical Reinforcement 12@100c/c Provide Horizontal Reinforcement 10@100 c/cProvide Top Reinforcement 10@200 c/c (B/W)

For Block Foundation, reinforcement of 25Kg/m3 is provided.

20MVA Transf fdn


Top Reinforcement 10@200 c/c (B/W)Length 3.15 mBreadth 2.35 mNo of bars along length 12No of bars along breadth 16Length of bars 72.60 mTotal weight @ 0.617 kg/m 44.79 kg

Length 3.15 mBreadth 2.35 mNo of bars along breadth 24No of bars along length 30Length of bars 216 mTotal weight @ 0.89 kg/m 192.24 kg

@100 C/CHeight 2 MNo. of bars along length 21 nos

Length of bars 227.64 mTotal weight @0.617kg/m 140.45 kg

Total Weight of bars 377.49 kg

Volume of foundation = 2 x 2.35 x 3.15 = 14.81

Reinforcement per cubic meter = 377.49 / 14.81 = 25.50

Reinforcement required at pedestal base

Net upward pressure at the base 75.55 KN/m2 = 83.05 - 0.3x 25

Partial factor of safety 2.2Moment at face of Block 9.44 KN-m/m = 75.55 x 0.5^2 / 2

Design Moment, Mu 20.78 KN-m/m = 2.2 x 9.44

Clear cover 50 mmEffective depth, d 245 mm

Area of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))^1/2Hence, xu = 12.04 mmand Ast1 = 240 mm2/mMininimum Ast for 0.12% reinf. 360 mm2/mMax spacing, 3d or 450mm = 450 mm

Provide 10 200 mm c/c at bottom = 393 mm2/m, O.K.

Provide 10 200 mm c/c at Top = 393 mm2/m, O.K.

Vertical Reinforcement 12@100 c/c

Horizontal Reinforcement 10

m3

kg/m3 > 25 kg/m3

f bars @

f bars @

20MVA Transf fdn


2. Design of wall foundation for rails

Shipping wt of transformer = 50850 kg= 498.84 KN

Calculation of Gravel loadL.L. on grating 2.94 KN/m2Wt of gravel 2.35 KN/m2Wt of grating 0.69 KN/m2

5.98 KN/m2Thickness of wall 0.400 mC/C distance of rail track 1.743 mLoad coming on unit length of wall 4.02 KN/m = 5.98 x ( 1.743 - 0.4)/2

Case I : When wheels run on two parallel tracks

350 1743 350

300 400 GL

21002000

200

2443

Final load combination for single wall1) DL due to equipment 124.71 KN = 498.84 / 4

124.71 KNConsidering unit length of wallVertical load 71.55 KN/m = 124.71 / 1.743

Dead wt of wall 21.00 KN/m = 0.4 x 2.1 x 25

Load from Gravel and Grating 4.02 KN/m96.57 KN/m

Factored vertical load/m, Pu 212.45 KN/m =2.2 x 96.57

Clear cover provided 50 mmEffective depth, d 344 mm

Minimum reinforcement required 0.2 % of gross areaReinforcement required 800 = 0.2/100 x 1000 x 400

Provide 12 125 mm c/c as Vert. & Horiz.Reinf. = 905 mm2/m, O.K.

Design of base pad

SBC at toe level for dead load only 68.67 KN/m2 = 68.67

Pressure due to overburden soil 36.79 KN/m2 = 2 x 18.39

Dispersed load width 6.343 m = (1743 + 2 / tan(45) x 2300)/1000

mm2/face

f bars @

20MVA Transf fdn


Moment at base 53.67 KN-m/m = (74.83 x(4.5/2+2.3))/6.343

Volume of concrete above GL 0.24 m3/m = 2 x 0.3 x 0.4

Volume of concrete below GL 1.93 m3/m = 2 x 1.8 x 0.4 + 2.443 x 0.2

Dead load raft & wall 54.22 KN/m = (0.24 + 1.9286) x 25

Total Vertical load 141 KN/m 498.84 / 6.343 + 54.215 + 4.02 x 2

2300

1743

6343

Maximum bearing pressure developed = 20.89 KN/m2 = 140.9/2.443 - 36.79

< 68.67 KN/m2 OK.Design of base pad

Net bearing pressure 15.89 KN/m2 = 20.89 - 0.2 x 25

Moment at middle of slab 6.03 KN-m/m = 15.89 x 1.743^2 / 8

Design moment, Mu 13.27 KN-m/m = 2.2 x 6.03

Clear cover provided 50 mmEffective depth, d 145

Area of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))1/2Hence, xu = 13.23 mm

and Ast1 = 264

Mininimum Ast for 0.12% reinf. 174Max spacing, 3d or 450mm = 435 mm

Provide 10 250 mm c/c both ways at top and bottom

= 314

Check for punching against one wall

Punching perimeter 12.686 m = 2 x 6.343

Effective area for punching 1.84 m2 = 12.686 x 145/1000

Punching load 408.110 KN =498.84/2+4.02x6.343+(2.1 x0.4x6.343)x25

Punching shear stress developed 0.488= 2.2 x 408.11x 1000 /(1.84x 1000 x 1000)

< 0.25 x sqrt(fck) = 1.118 N/mm2, O.K.

45º

mm2/m

mm2/m

f bars @

mm2/m, O.K.

N/mm2

20MVA Transf fdn Page 7


3. Design of transformer pit wall

150

300 FGL

550

750400 0

200

950

Load calculation

1) Gravel load 2.35

2) Grating load 0.69

3) L.L. 2.94

5.98

Coeff. of earth pressure, K0 1.00 1 - sin(0)

1 + Sin (0)

Soil pressure at the bottom of wall 13.80 = 1 x ( 0.75 x 18.39)

Surcharge 2000

= 19.62

Earth pressure due to surcharge,q0 19.62 = 1 x 19.62

750

0

0.00 KN/m2 13.80 KN/m2 19.62Water pressure Earth Pressure at rest Lateral pressure due to surcharge

55010.12 0.00

200

13.80 0.00

Earth Pressure at rest Water pressure

KN/m2

KN/m2

KN/m2

KN/m2

KN/m2

KN/m2

KN/m2

KN/m2

KN/m2



Check for OverturningWeight of concrete per metre of wall lengtha) Pedestal 3.19 KN/m = 0.85 x 0.15 x 25

b) Raft 4.75 KN/m = 0.95 x 0.2 x 25

Weight of overburden soil per metre of wall length 8.09 KN/m = (0.95 - 0.15) x 0.55 x 18.39

Weight due to surcharge 7.85 KN/m = 19.62 x 0.4

Total Oil Weight 7.20 KN/m =14100 x9.81/1000/9.6/2

Total vertical load 36.77 KN/m =3.19+4.75+8.09+5.98x0.95+7.85+7.2

Restoring moment about toe of fdn 15.72 KN-m/m = 0.9 x 36.77 x 0.95 /2

Overturning momentMoment from soil side of pit 6.81 KN-m/m =19.62x0.75^2/2+13.8x0.75^2/6+0x0^2/6

Moment from other side of pit 0.23 KN-m/m =10.12x(0.2)^2/2+(13.8-10.12)x(0.2)^2/6

Net overturning moment 6.58 KN-m/mF.O.S. against Overturning 2.39 >2.2, Hence O.K.

Check against sliding

Maximum horizontal shear 19.89 KN/m =19.62x0.75+13.8x0.75/2

Cohesion, c = 34.34Coefficient of Friction = 1.00

Resisting passive pressure, P = 82.47 =2 x 34.34 x 1+18.39*0.75*1

Minimum area = 0.75 m2/m = 0.2 + 0.55

Max. frictional resistance = 61.85 KN/m = 82.47 x 0.75

F.O.S. against Sliding = 3.11 = 61.85 / 19.89

> 2.2, Hence O.K.

Design of wallClear cover provided 50 mmPartial factor of safety 2.2Effective depth, d 95 mm

Soil pressure at the bottom of wall 10.12 = 1 x 0.55 x 18.39

550

00.00 KN/m2 10.12 KN/m2 19.62 KN/m2

Water pressure Earth Pressure at rest Lateral pressure due to surcharge

Design Moment, Mu 7.65 KN-m/m = 2.2 x ( 0.5 x 10.12 / 3 + 19.62/2 ) x 0.55^2

Area of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))^1/2Hence, xu = 11.80 mm

and Ast1 = 235

Minimum Ast in wall 0.2% = 300

Ast / face = 150Provide 10 200 mm c/c as Vert. Reinf.

= 393

KN/m2

= tan2(45 + 0/ 2) Deg.

KN/m2

KN/m2

mm2/m

mm2/m

mm2/mf bars @

mm2/m, O.K.



Design of internal wall face(Considering water inside & no earth outside during construction stage)

850

8.50 KN/m2 0Top of raft

Moment at the base due to water 1.02 KN-m/m = 0.5 x 0.85 x 10 x 0.85 x ( 0.85/3+0)

Design Moment, Mu 2.25 KN-m/m = 2.2 x 1.02

Area of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))^1/2Hence, xu = 3.3 mm

and Ast1 = 67


Ast / face = 150Provide 10 200 mm c/c as Vert. Reinf.

= 393

Horizontal reinforcement

Providing pt = 0.2 %


Ast / face 150Provide 8 250 mm c/c per face

= 201W3

Design of base slab

Wt of soil outside the pit,w1 4.05 KN/mWt of soil inside the pit,w2 0.0 KN/mNet design moment, Mu 5.85 KN-m/m Soil 0

= 0.5 x 13.8 x 0.75^2 / 3 + 19.62 x 0.75^2/2-(4.05-0)*0.475/2 550 W1

Wt of wall & gravel 13.92 KN/m soil W2

Design vertical load, Pu 17.97 KN/m 200

Pressure due to overburden soil 13.80 400

= 0.75 x 18.39

Bearing pressure 44.01 475

= 17.97 / 0.95 + 5.85 x 6 / 0.95^2 - 13.8

SBC at toe level 49.05> 44.01 Hence Ok

Net bearing pressure 39.01 = 44.01 - 0.2 x 25

Design moment, Mu 6.87 KN-m/m = 2.2 x 39.01 x 0.4 ^2 / 2

Effective depth, d 146 mmArea of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))^1/2Hence, xu = 6.67 mm

and Ast1 = 133

Minimum Ast in slab 0.12% = 240

Ast / face = 120Provide 8 300 mm c/c per face

mm2/m

mm2/m

mm2/mf bars @

mm2/m, O.K.

mm2/m

mm2/mf bars @

mm2/m, O.K.

KN/m2

KN/m2

KN/m2

KN/m2

mm2/m

mm2/m

mm2/mf bars @



= 167 mm2/m, O.K.


CLIENT POWER GRID CORPORATION OF INDIA LIMITED SHYAMA POWER (I) LTDPROJECT BIHAR SUB TRANSMISSION SYSTEM, PHASE II, PART II DESIGN NO.- 1000SUBSTATION 132/33KV Runnisaidpur S/S

Transformer load 50850 kgLoad for Pulling Block 5% of 50850 = 2542.50 kg 25Size of Pulling Block 1.00 m x 1.00 m

300GL

2000

200

300 1000 300

1600Weight of concretewt of concrete above GL = 0.3 x 1 x 1 x 25 7.50 KNwt of concrete below GL = (1.8 x 1 x 1 + 0.2 x 1.6 x 1.6)x25 57.80 KNTotal wt of concrete 65.30 KNWeight of soil = 1.8 x (1.6 x 1.6 - 1 x 1) x 18.39 51.65 KNTotal weight due to soil= 51.65 KN

Coefficient of Passive pressure = (1 + Sin 0)/(1-Sin 0) = 1.00Passive pressure = 1 x 1.8 x 18.39 = 33.11 KN/m2Moment due to Passive pressure = 1 /2 x 33.11 x 1.8 x 1.8/3 = 17.88 KNm

Passive pressure = 1 x 0.2 x 18.39 3.68 KN/m2Moment due to Passive pressure = 1 /2 x 3.68 x 0.2 x 0.2/3 = 0.02 KNm

Applied Moment = 25 x 2.3 = 57.50 KNmResultant moment = 57.5 - 17.88 - 0.02 = 39.60 KNmTotal Vertical load = 65.3 + 51.65 = 116.95 KNResisting moment = 116.95 x 1.6/2 = 93.56 KNmFOS = 93.56/39.6 = 2.36 > 2.2

Reinforcement calculation

Total Vertical load 52.50 KNHoriz. Force in y-direction,SFy 25 KNMoment about major axis ,Mx = 25 x 2.1 52.5 KNmShear parallel to base channel, SFx 0 KN

= (300 + 2000 - 200)/500+1000/30 37.53 mmMoment about minor axis ,My 1.97 KNmActive moment about the base of pedestalMux = 2.2 x 52.5 115.50 KNmMuy = 2.2 x 1.97 4.34 KNm

4. Calculation for Pulling Block

Minimum eccentricity,emin


CLIENT POWER GRID CORPORATION OF INDIA LIMITED SHYAMA POWER (I) LTDPROJECT BIHAR SUB TRANSMISSION SYSTEM, PHASE II, PART II DESIGN NO.- 1000SUBSTATION 132/33KV Runnisaidpur S/STotal comp. force at bottom, P = (300 + 2000 - 200)/1000 x1x1x 25 52.50 KNPu = 2.2 x 52.5 115.50 KNMinimum percentage of steel required, pt,min 0.8 %

X-sectional area of column required = 115.5 x 1000 /(0.4 x 20 + 0.67 x 415 x 0.8/100) 11296.51

Minimum area of steel required 90.37

Area of Steel(As) 1356.48

Percentage of steel, p 0.136 %Clear Cover provided 50 mmd'/D 0.05

0.006

0.007

0.01

200.0 KN-m

0.01

200.0 KN-mPuz 9422 KNPu/Puz 0.012

1Interaction ratio 0.578 + 0.022 0.599 < 1 , OK

Provide 8 250 C/C as lateral ties

Design of base slab

Self wt of raft = 1.6 x 1.6 x 0.2 x 25 = 12.80 KNwt of pedestal = 2.1 x 1 x 1 x 25 = 52.50 KNwt of soil = (1.6x1.6 - 1x1) x (1.8 x 18.39) = 51.65 KNTotal load, P = 12.8 + 52.5 + 51.65 = 116.95 KNArea of fdn = 1.6 x 1.6 = 2.56 m2Applied Moment = 25 x 2.3 = 57.50 KNmResultant moment = 57.5 - 17.88 - 0.02 = 39.60 KNmBearing pressure =116.95/2.56+39.6x 6/1.6x1.6^2 - 36.79 = 66.90 KN/m2

< 85.84 KN/m2

Net bearing pressure = 66.9 - 25 x 0.2 = 61.90 KN/m2

Design moment, Mu = 2.2 x 61.9 x 0.3^2/2 6.13 KN/mEffective depth, d 145 mmArea of Steel, Ast = Mu/(0.87fy(d-0.416xu), where xu/d=1.202+-(1.4446-6.67735Mu/fckbd2))^1/2Hence, xu = 5.98 mm

and Ast1 = 119

Minimum Ast in slab (0.12%) = 240

Ast / face 120Provide 10 300 mm c/c per face

= 262

mm2

mm2

12 nos 12f bars mm2

Pu/fckbD

p/fck

Referring to chart 44 of SP16, Mux1/fckbD2

Mux1

Referring to chart 44 of SP16, Muy1/fckbD2

Muy1

αn

f @

mm2/m

mm2/m

mm2/mf bars @

mm2/m, O.K.


SHYAMA POWER (I) LTDDESIGN NO.- 1000

KN


SHYAMA POWER (I) LTDDESIGN NO.- 1000

20MVA transf fdn Page 12

CLIENT POWER GRID CORPORATION OF INDIA LIMITED SHYAMA POWER (I) LTDPROJECT BIHAR SUB TRANSMISSION SYSTEM, PHASE II, PART II DESIGN NO.- 1000SUBSTATION 132/33KV Runnisaidpur S/S

Volume of transformer oil = 17200 LitresVolume of Soak Pit (Net) = 1.3x 17200 = 22360 LitresDepth of Soak Pit = 0.55 m

Surface Area of Soak Pit required = 22.36/0.55 = 40.65

Area occupied by Transformerfoundations & cooling system foundations = 3.150 x 2.350 + 2 x 0.4 x 2.775

= 9.62

Therfore, Gross area of Soak Pit required = 40.65+ 9.62 = 50.28

Inside Gross area of Soak Pit = 5.2 x 2.3 + 1.450 x 6.2+3x7 +5.8x1.45+1.4x4.4

= 56.48

5. Soak Pit Calculation:

m2

m2

m²

m2 > 50.28 m2

trfrfdn-20 mva(runnisaidpur)

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