Admin.. Water Tank

8/7/2019 Admin.. Water Tank

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Design of Waffle walls of water tank6.2

1.8 1.8

0.2

0.35 0.15

1.65

1.3

0.35

Properties of materials

Grade of concrete = M25

25 MPa

8.33 MPa

Unit weight of concrete = 24000

Grade of steel = Fe500

500MPa

Permissible strength of steel = 150 MPa

Modular ratio 'm' = 10

k = 0.357j = 0.881

Q = 1.311

Density of water 'w' = 10000

Characteristic strength of concrete fck

=

Permissible strength of concrete cbc

=

N/m3

Ultimate strength of steel fy=

N/m3


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Design of Waffle walls of water tank

Alowable stress from Table 1 of IS3370 part 2

Allowable bending tensile stress 1.8

Allowable direct tensile stress 1.3

Max. Force on Waffle wall due to water = 8450.0 N

Bending Moment in the Waffle wall = 3661.7 N-m

since tension is on water face, the design has to be done on basis of uncracked section.

Hence, total thickness = D = 110.5 mm

Provide total thickness = D = 200 mm

OK

Clear cover for the wall = 25 mm

Effective depth of wall = d = 170 mm

Ast req = 163.0 mm 2

Minimum Ast = (As per clause 7.1 IS 3370 PART 2) 428.6 mm 2

Ast provided = 10 dia @ 130 mm c/c thus providing 604.2

OK

ct ' N/mm2

tc

' N/mm2

mm2


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DESIGN OF WATER TANK FOR ADMINISTRATION BUILDING

A 6.3

2.1

2.5 4.2 0.2

A

1.8 2.6 1.8

PLAN OF THE WATER TANK

2.5

0.12

1.65

2.1 0.2

0.35

0.3

SECTION A-A


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Properties of materials

Grade of concrete = M25

25 MPa

8.33 MPa

Unit weight of concrete = 24000

Grade of steel = Fe500

500 MPa

Permissible strength of steel = 150 MPa

Modular ratio 'm' = 10

k = 0.357

j = 0.881

Q = 1.311

Density of water 'w' = 10000

Design of walls of water tank

Edge condition used for design purpose is tank with walls hinged at top & bottom.

The table 6 of IS:3370 (Part 4) corresponds to these edge conditions.

Longer plan dimension of water tank 'b' = 4.30 m

Shorter plan dimension of water tank 'c' = 2.30 m

Height of the water tank 'a' = 1.86 m

b/a = 2.55

c/a = 1.27

2.30 E

C A

1.86F

4.30 D B

Characteristic strength of concrete fck

=

Permissible strength of concrete cbc

=

N/m3

Ultimate strength of steel fy=

N/m3


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BENDING MOMENT

UsingTable No. 6 is 3370 (part 4) 1967

For b/a = 3 and c/a = 1.5

line CD at y = 0 line AB at y =b /2 line EF at z=0

Mx My Mx My Mx My

x / a

1 / 4 0.035 0.010 -0.007 -0.035 0.014 0.013

1 / 2 0.057 0.015 -0.011 -0.057 0.027 0.020

3/ 4 0.051 0.013 -0.010 -0.051 0.029 0.017

-ve sign means bending moment causing tension on inner face of wall

+ve sign means bending moment causing tension on outer face of wall

Maximum coefficient for moment in vertical direction 'Mx'

1. Inner face (at mid height of y=b/2) -0.011

2. Outer face (at mid height of y=0) 0.057

Maximum coefficient for moment in horizontal direction 'My'

1. Inner face (at mid height of y=b/2) -0.057

2. Outer face (at quater height of y=b/2) -0.035

SHEAR FORCE

UsingTable No.7 is 3370 (part 4) 1967

Maximum shear force at corner 20179.85 N

Maximum shear force at corner 20179.85 N

Corresponding shear force at mid height 12468.40 N

Mh = horizontal moment = My * w * a 3

Mv = vertical moment = Mx * w * a3


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DESIGN OF SECTION IN HORIZONTAL DIRECTION

Governing Bending moment / Shear force

Mh = 3667.87 N-m

SF = 20179.85 N

Clear cover to reinforcement = 25 mm

Thickness of the wall = D = 200 mm

Effective depth of the wall = d= 170 mm

Bending tensile stress = M / Z = 0.550

Direct tensile stress tc = V / b d = 0.119

Alowable stress from Table 1 of IS3370 part 2


Allowable direct tensile stress 1.3

+ = 0.397 < 1 OK

Considering effect of bending only required effective depth = 110.57 mm

< 200.00 mm

OK

Maximum horizontal moment, Mh = 3667.868 N-m

Maximum Shear Force (Vmax) = 20179.85 N

Corresponding Shear Force (Vcorr) = 12468.40 N

Net Moment Mh' = Mh - Vcorr ( d - D/2 ) = 2795.08 N-m

Ast req = 258.96

Minimum Ast = (As per clause 7.1 IS 3370 PART 2) 542.86


OK

DESIGN OF SECTION IN VERTICAL DIRECTION

Thickness of the top slab 200 mm

DL on the wall = 6480.000 NWt of wall up to its mid ht. = 4464.000 N

vertical thrust in wall at mid ht.= 10944.000 N

B M Mv at mid of wall = 3667.868 N-m

Net Moment Mv' = Mv + T (d -D/2) = 4433.948 N-m

Considering effect of bending only required effective depth = 121.57 mm

< 200.00 mm

OK

Ast req = 124.418

Minimum Ast = (As per clause 7.1 IS 3370 PART 2) 542.857


OK

N/mm2

N/mm2

ct ' N/mm2

tc

' N/mm2

ct '

tc

'

ct

tc

mm2

mm2

mm2

mm2

mm2


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Bottom slab design of water tank

Material

m 10.00 fck 25.00

Conc Grade M25 fy 500.00Steel Grade Fe500

Unit wt of Conc 24.00 min clear cover 25 mm

xu, max/ d 0.46

Dimensions

2525

3100

325

Loads

Member Fac L (m) B (m) D (m) (kN/m3) w (kN/sqm)

Self Wt 0.325 24.00 7.80

Finishing 0.050 24.00 1.20

Weight of water of height 1.65m 1.650 10.00 16.50

Weight of partition wall 1.300 24.00 31.20

IL 0.00 0.00

total load DL + IL 56.70

N/mm2

N/mm

2

kN/m3


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Design

Load 56.70 kN/sqm

Lx 2.53 m

Ly 3.10 m

Ly / Lx 1.23

Condition three edges discontinuous (one short edge continuous)

using table no 26 of IS456:2000

Mx My

+ve -ve +ve -ve

for Ly/Lx 1.20 0.06 - 0.04 - 0.06

for Ly/Lx 1.30 0.07 - 0.04 -

0.061 0.043 0.057

Moment 21.93 15.54 20.61

Since Moment produce tension on water face thickness of concrete from point of view of cracking is given below


Considering effect of bending only required depth = 270.37 mm

Provide total thickness D = 325 mm OK

d= 295 mm

Ast req = 562.6 mm2 398.8 mm2 528.6 mm2

min Ast 766.1 mm2 766.1 mm2 766.1 mm2

Ast Provided = 785.4 mm2 785.4 mm2 785.4 mm2

OK OK OK

Mx My

+ve -ve +ve -veDia 10 10 10

Spacing 100 100 100

ct ' = N/mm2


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Top slab design of water tank

Material

m 10.00 fck 25.00

Conc Grade M25 fy 500.00Steel Grade Fe500

Unit wt of Conc 24.00 min clear cover 25 mm

xu, max/ d 0.46

Dimensions

2525

6200

200

Loads

Member Fac L (m) B (m) D (m) w (kN/sqm)

Self Wt 0.200 24.00 4.80

Finishing 0.050 24.00 1.20

Additional for Baffle walls 1.300 24.00 31.200.00

IL 1.50 1.50

Limit State of Collapse 1.5 DL + 1.5IL 58.05 kN/sqm

N/mm2

N/mm2

kN/m3


10/10

Design

Load 58.05 kN/sqm

Lx 2.53 mLy 6.20 m

Ly / Lx 2.46

Condition

using table no 27 of IS456:2000

Mx My

+ve -ve +ve -ve

for Ly/Lx 2.00 0.12 0.03

for Ly/Lx 2.50 0.12 0.02

0.122 0.021

Moment 45.02 kN-m 7.70 kN-m

Design

deff 170 mm 160 mm

Ast Prov.

Dia 10 10

Spacing 100 100

Ast 785 785

p% 0.39 0.39

p% min 0.12 0.12

OK OK

Mu, linConc 95.9 kN-m 84.9 kN-m

Steel 52.7 kN-m 49.3 kN-m

Chk for Ductility OK OK

Mu, perm 52.7 49.3

OK OK

Deflection Check

Max % of reinforcement provided 0.39fs 248

Mod Factor Factor as per IS:456, 2000 Fig 4 1.50

Basic Span to depth ratio as per Cl 23.2.1 (a) of IS;456 20

max span to depth ratio 30.0

Actual Span to depth ratio 14.9

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