water tanks 1

8/18/2019 Water Tanks 1

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WATER TANKS (Part 2)

MAINAKMALLIK


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2

• DESIGN OF CIRCULAR WATER TANK

RESTING ON GROUND WITH RIGID

BASE AND FLEXIBLE BASE


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Joints

• Joints are the connection betweentwo parts of the structuralcomponent.

• Commonly Three type of Joints arecommonly in water tanks :

• A Mo!ement Joints

• " Construction Joints

• C #emporary $pen Joints


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Mo!ement Joints

• A mo!ement %oint is inten&e& toaccommo&ate relati!e mo!ementbetween a&%oinin' parts of a structure (

special pro!ision is ma&e to maintainthe water ti'htness of the %oint.

• #hree types of Mo!ement Joints:

•

A Contraction Joint• " )*pansion Joint

• C +li&in' Joint


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#wo #ypes of Contraction Joint:

, Complete Contraction Joint

2. -artial Contraction Joint


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)*pansion Joint


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C$N+#/C#I$N J$IN#+


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•

Salient features :,. #he position shoul& be &e0ne& by &esi'ner.2. 1ull structural continuity is assume& in&esi'n an& shoul& be realie& in practice.3. #he concrete at %oints shoul& be bon&e&properly.4. #he surface of the earlier pour shoul& berou'hene& to increase bon& stren'th an& topro!i&e a''re'ate interlock.

5. #he %oint surface shoul& be cleane& an&&ampene& si* hour prior to new concretin'.


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Circular Tans Restin! "n#roun$


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,6

• When tan is %lle$ &ith &ater thehy$rostatic &ater pressure &ill try toincrease the $ia'eter at any section

• This &ill $epen$ on type of oint atthe unction of &all an$ *ea'

• When the oints at *ase are +e,i*le-

hy$rostatic pressure in$uces'a,i'u' increase in $ia'eter at*ase an$ no increase in $ia'eter attop

• When the oint at *ase is ri!i$- the*ase $oes not 'o.e


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7

• 7e8ecte& shape of #ank with 1le*ible Joint

9

A

"

C

7",


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2,

/esi!n of Circular Tans restin!on !roun$ &ith ri!i$ *ase


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22

• /ue to %,ity at *ase of &all- the

upper part of the &all &ill ha.ehoop tension an$ lo&er part*en$ lie cantile.er

• 0or shallo& tans &ith lar!e$ia'eter- hoop stresses are .erys'all an$ the &all act 'ore liecantile.er

• 0or $eep tans of s'all $ia'eter thecantile.er action $ue to %,ity at the*ase is s'all an$ the hoop action is

pre$o'inant


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• The e,act analysis of the tan to

$eter'ine the portion of &all in&hich hoop tension ispre$o'inant an$ the other

portion in &hich cantile.eraction is pre$o'inant- is$i1cult

• Si'pli%e$ 'etho$s of analysis

are Reissner3s 'etho$

2 Carpenter3s si'pli%e$ 'etho$

4 Appro,i'ate 'etho$


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2

• 6S co$e 'etho$

• #ables 6;,< an& ,, of I+ 33=< part I>

'i!es coe?cients for computin'hoop tension; moment an& shear for!arious !alues of 92@7t

•

9oop tension; moment an& shear iscompute& as

# coe?cient B γ w97@2

M coe?cient Bγ w9

3

> coe?cient Bγ w9

2


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2=

• #hickness of wall reuire& is compute& from "Mconsi&eration

where;

D E σcbc %k

%,FBk@3

b ,


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2G

• 6S co$e 'etho$

• $!er all thickness is then compute& as

t & H co!er. • t 7

• t3


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26

• 6S co$e 'etho$

• /istri*ution steel an$ .ertical

steel for outer face of &all isco'pute$ fro' 'ini'u' steelconsi$eration

• Tensile stress co'pute$ fro'the follo&in! e7uation shoul$*e less than the per'issi*le

stress for safe $esi!n stc

A)1m(t1000

T

−+

=σ

the per'issi*le stress is as per ta*le of6S 4489 (Part 2) : 299;


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3<

• 6S co$e 'etho$

• Tensile stress $ue to *en$in! co'pute$fro' the follo&in! e7uation shoul$ *e lessthan the per'issi*le stress for safe $esi!n

• o$ulus consi$erin! the e?ectof reinforce'ent

• @ase sla* thicness !enerally .aries fro'9'' to 29 '' an$ 'ini'u' steel is$istri*ute$ to top an$ *otto' of sla*

where

z

M

=σ cbt


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3,

/esi!n Pro*le' No on CircularTans restin! on !roun$ &ith

Ri!i$ *ase


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• A cylin$rical tan of capacity8-99-999 liters is restin! on !oo$unyiel$in! !roun$ The $epth of tan

is li'ite$ to ' A free *oar$ of 499'' 'ay *e pro.i$e$ The &all an$ the*ase sla* are cast inte!rally /esi!nthe tan usin! >2 concrete an$0e5 !ra$e steel

• /ra& the follo&in!

• Plan at *ase• Cross section throu!h centre of tan


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• Step : /i'ension of tan

•

B= 94 = 58 an$ .olu'e =899 '4

• A=899D58 = 5;5 '2

•

/=√

(5 , 5;5Dπ

) = 488≈

5 '


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• Step 2: Analysis for hoop tensionan$ *en$in! 'o'ent

• "ne 'eter &i$th of the &all isconsi$ere$ an$ the thicness of the&all is esti'ate$ as t=49BF9 =; ''

• The thicness of &all is assu'e$

as 299 ''•

•

( ) 9.7

2.014

7.4

.

22

=

×

=t D

H


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3G

• Step 2: Analysis for hoop tension an$ *en$in! 'o'ent(Cont$)

•

• Referrin! to ta*le ; of 6S4489 (part 6)-the 'a,i'u' coe1cient for hoop at 9GBtension = 98

• T'a,=98 , 9 , 58 , 8 =;8 N•

• Referrin! to ta*le 9 of 6S4489 (part 6)-the 'a,i'u' coe1cient for*en$in! 'o'ent = 995G (pro$uces tension on&ater si$e) at 9B

• >'a,= 995G , 9 , 584= N'•

• Referrin! to ta*le of 6S4489 (part 6)-the 'a,i'u' coe1cient for S0=985

• S0=985H9H582=455N


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• Step 4: /esi!n of section:• 0or >2 concrete σc*c=- 0or

0e5 steelσ

st=9 >Pa an$'=9; for >2 concrete an$0e5 steel

• The $esi!n constants are:

• =(D4)=9G•

I= σ

c*c = 4• E?ecti.e $epth is calculate$ as

mm= x

x=

Qb

M =d 99.83

10001.52

1015.15 6

418.0

1305.898.10

8.510.98=

+×

×=

σ +mσ

mσ =k

st cbc

cbc


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4<

• Step 4: /esi!n of section: (Cont$)• et o.er all thicness *e 299

'' &ith e?ecti.e co.er 44 ''

$pro.i$e$=G8 ''

• Spacin! of 2 '' $ia'eter *ar=

•

• (>a, spacin! 4$=9'')

• Pro.i$e L2M2 cDc as .erticalreinforce'ent on &ater face

2

st

st mm= x x0

x= jd σ

M = A 802

167.87130

1015.15 6

cmmc= x

/140802

1000113

2904mm

125

1000113=

x

• Step 4: /esi!n of section: (Cont$ )


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4,

Step 4: /esi!n of section: (Cont$)• Boop steel:

• Spacin! of 2 '' $ia'eter *ar =

• Pro.i$e L2M8 cDc as hoop reinforce'ent

on &ater face

• Actual area of steel pro.i$e$

2

st

st mm= x

=σ

T = A 1456

130

10189.275 3

1

ccmm= x

/77.61456

1000113⋅

2

st mm= x

= A 1506

75

1000113


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i i* i l


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• Step : /istri*ution Steel:• >ini'u' area of steel is 925O of concrete

area• Ast=(925D99) ,999 , 299 = 59 ''2

• Spacin! of '' $ia'eter *ar =

• Pro.i$e L M 99 cDc as .ertical $istri*utionon the outer face

c/mmc.7.104480

1000x24.50=


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• Step : @ase sla*:• The thicness of *ase sla* shall *e

9 '' The *ase sla* rests on %r' !roun$-hence only 'ini'u' reinforce'ent ispro.i$e$

• Ast=(925D99) ,999 , 9 = 4G9''2

• Reinforce'ent for each face = 9''2


• Pro.i$e L M 29 cDc as .ertical an$horiontal $istri*ution on the outer face

c/mmc.279

180

1000x24.50=


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,2φ #=5c@c


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4

/esi!n Pro*le' No2 on CircularTans restin! on !roun$ &ith

+e,i*le *ase

/ i i l t t t


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4=

• /esi!n a circular &ater tan to

hol$ -9-999 liters of &ater

Assu'e +e,i*le oints *et&eenthe &all an$ *ase sla* A$opt >2concrete an$ 0e 5 steel

• Setch $etails ofreinforce'ents


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4G

• Step : /i'ension of tan

• olu'e of tan =9 '4

• Assu'e B= 5

• A=9D5 = 2222 '2

• /= √(5 , 2222Dπ) = 258 ≈2'


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• Step 2: Analysis for hoop tension• "ne 'eter &i$th of the &all is

consi$ere$ an$ the thicness of the&all is esti'ate$ as

• t=49BF9 = ''• The thicness of &all is assu'e$

as 299 ''•

•

81.82.05.12

5.4

Dt

22

≈=×

=


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• Step 2: Analysis for hoop tension

• Referrin! to ta*le 2 of 6S4489 (part6)- the 'a,i'u' coe1cient for hooptension = 9G;8

• T'a,=9G;8 , 9 , 5 , G2 =;G94 N

• Referrin! to ta*le of 6S4489 (part 6)-the 'a,i'u' coe1cient for shear at *ase=99;G

•

Shear=9;GQ9Q52=;55 N

•


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• Step 4: /esi!n of section:• 1or M25 concrete• σcbcG.5; 1or 1e4,5 steel σst,3< M-a• m,


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• Step 5: Chec for tensile stress:

• Per'issi*le stress = 4 ND''2 σct Safe

• Chec for Shear Stress:

2

st

ct mm N =

)x( + x

x=

)A(m+t

T =σ /0.91

1608110.982001000

10196.03

11000

3

−−

2ct mm N =

x

x=bd

V = /0.116

1671000

1019.44 3

τ

St /i t i* ti St l


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• Step : /istri*ution Steel:• >ini'u' area of steel is 925O of concrete

area•

Ast=(925D99) ,999 , 299 = 59 ''2



• Ast-pro.$=

c/mmc.7.104480

1000x24.50=

502s!.mm100

100050.24=

x

2

.

.,

/246.0

0.3%1000x167

100502

mm N

= x p

perm

prod t

=

=

τ


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5

• Step : @ase sla*:• The thicness of *ase sla* shall *e

9 '' The *ase sla* rests on %r' !roun$-hence only 'ini'u' reinforce'ent ispro.i$e$

• Ast=(925D99) ,999 , 9 = 4G9''2

•Reinforce'ent for each face = 9''2



c/mmc.279180

1000x24.50 =


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5=


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5G

A TP6CA /RAW6N#


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