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IS :,d requ ;rer:',ents.

':;.,1.1/"'01'0:15 A:;gregates

tile, bloalCo clay aggrcg1!\cs ~ ! : : I . ! ~ i n t e n ~ d flyasllaggregates, be allowed for paris ef SIJUCl:J;'e either incouta':, v, ith tl.e liquid:' OJ', ~ H l ) ;,1::e:. (;!lclosing the:{J;'.ce above tb: liquid.3.2 Joining r.1a(erialsJoint f'il:CI';. joint sealir,gslJall conF:rm lu the rcqdltCf l ! f : I IS 01 ' l . i ~ . l l 1 l \ i J H j i ~ , ! . Sliind"' lL OiLer je i r"i ; ' f : ' : c : ; : : , - i ~ : l , ~ ; . : c 1 t liSpz)lyurctiJanc and s i l i c o r . , ~ b:,scc s c ; d ~ " l ' . S I ~ U l y ab o beu:,ed provided there 2fC: salis!,::.:.":;" '.h!;\ ('i. their

4 EXPOSURE C O N D I T r O ~ F0f the rJrpose of this S l ~ i l d : l ! ' d . rc:o!S (f tile struC1ureretaining the liquid or enclosing thl' sp:1ce above theCGlldi:ion

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IS 3370 (Part 1) ; 2nD')1i.;ble 1 \linimum Ccmtut Content, i\lriXil1lU!ll

Water Cement Ratio and !\Iinimlllll Grade of Concrete

[Fore;vord, ::md C!mlse 5(a)]

w ~ d ! ~ , ~ K c 0 r d l n g to the cum paction anclforn:hargc of the soil an d the condition of [hI:

s:ructure during construction and in serviCe,1\0 .-eiief shC>UlJ be given for beneficial soil

SI Concrete ]'.linimum Maximum ]'.lillimulIINo. Cement Free Water Grade of

Content Cement COllccctekg/m' Ratio

(I ) (2 ) (3 ) ( ~ ) (5 )i) Plain concr ete 250 0_50 M20ii) Reinforced 320 0.45 M30

concreteiii) Prestressed 360 0.40 M40

concreleNOTES1 Cement content prescribed in this table is irrespectivt: of til,:"rades of cement llnd it is inclusive of additions mentioned in5.2 of IS 456, The additions such as flyash or ground granulatedbillS! furnace slag may be taken inro aCcollnt in the concret ecomposition with respect to the cement content and watercement ratio if the ~ i t a b i ! i t y is established and as long as themaximum amounts taken into account do not exceed the limitofpozzolana and slag specified in IS 1489 (Part I) and IS 455respectively,2 For sm:;!1 capacilY tanks up to 50 m' at localions when: then:is difticulty in providing 1'.130 grade concrete, the minimum! ? r a , ~ e of cC':1cret

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IS 3370 (Pari 1) : 200'or the structure into sm:::.lkr comp::irtments andpro',ision of j o i [ i ~ s to Ol.llkl pi;>es and otherfittings. Joints in structures in miningsubsidencc arC:15 will nced s r e c ~ , , 1 ! consideration to f'rO\'id,., for extra movement.

e) II/jurious Soils Chemical analysis of thesoil and ground water is essential in caseswhere injurious soils 8 CAUSES AND CONTROL OF CRACK[NG8.1 Camcs8.1.1 Effects ofApplied LnodsDirecl Dr /leAUlal t e n ~ i , \ ; l :n con,-rete arising from,,;;:L::c ex(crn::] senj({ leads, fro!:l ~ e f ! ! p c , a t u r : : ,

nls due \() solar fRoial ion, or from thecontair.mcnt of liquids allernperatures above ambient,may cause cracking in the concrete,

Changes in the temperature of the concrete alldreinforcement and in the moisture conlent of theconcrete cause d i m e n ~ i o n a l changes whi.::h, if resistedinlCrnally or ,;xternally m:l"y Ci:1ck the concrete. Thedislrihtl1ion and width of sllch cracks may be controlledby reinfolcell;cm, l\}gctlier with lhe prO\ision of the.movement joints. Heal is evolved as cement hydrates,and the temperature will rise for a day or more, aftercasting and then fall towards ambient. Cracking usuallyoccurs at this time, while the concrete is still weak.Subsequent lower ambient temperature and loss ofmoisture when the concrde is,mature will open thesecracks although Ihe los$ of moisture at the surface underexternal drying condilIons is usually low. A structurebuilt in the summer but nU l lillcd or:l.ll external structurestanding empty wil! usually b;.' subjected to greaterdrops in temperature than the sarne structure filled.8.2 Methods of ControlS.2.1 Plain concrel\.'. liquid retaIOlng structures ormembers may be designed by allowing direct tensionin plain concrete. the permissible tensile stress [o r M2 0and M25 conerel

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IS 3370 (Part 1) : 2(1)9A stru:Wre :,) underground water prcssun:shall he dcsign'2d W rC:5i"t tloZttation as given in 7.2(b).10 JOINTS10.1 Joints sbJ.ll be categorized as follows:

a) Movemen! Joints - A movement joint isintended to Jc;';oJ1lfl1odate relative movementbetween adjoining parts of a structure, specialprovisions being made to maintain [he water-2tightness of the joint. In elevated structureswhere restraint is small. movement joints maynot be required. There are three categories ofmovement joints:J) . Comracr!rm joint - A movement joint

with a deiiberale discontinuity but noinitial gap between the concrete on eitherside of the joint, the joint being intendedto accommodate contraction of theconcrete (see Fig. 1)..A distinction should be made between acomplete contraction joint (see Fig. lA)'and a partial contraction joint (see Fig.1B). While the complete contraction

.' j o i n t ~ are not fcSlnlined to movement andare intended to accommodate onlycontraction of the concrete, the partialcontraction joints provide some restraintbut are intended to accommodate somecontracti:lrl of CO;1crete. In completec ( l n t ~ a c t i o n joints b o t ~ concrete and

IJOINT SEALINGCOMPOUNDDISCONTINUITY INCONCRETE BUT NO JINITIAL GAP . WATER BAR- I I

~ ~ l . . ~ z j 'l { . .

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IS 3370 (Part 1) : 2009I ~ ~ ! T I ; ' , ~ G.A.PJ : ) i ~ ~ T S ~ A l l t J G - - ; - i ' - - ~ COMPOUND STRIP P;":i\TIt\GV.j,t.,TER BAR - - ~ ~ _ . -1 -1-+-_If'.:IT1AL GAP

JOINT SEALINGCOL1POUND

\ \\ K)INT FILLER

.... .

"..

J

\1D 1 S C O N T I r \ j U ~ T Y IN80TH CONCRETE AND STEEL

2A 28FIG. 2 TYPICAL EXPANSI0" JO:';TS

3) Sliding j o in l -A movcmentjoirn which Tht' position of construction joints should beallows two siruclural m c ' i 1 1 b c r ~ to s l i d ~ 'p,ufieJ t1:e dcsigr.a. Full strucLUr;ilrelative to one another with minimal continuilY is assumed in d.:sign at therestraint. This has complet.: discontinuity C(),;C:irueli,-;n join! and should be reaiized inin both r e i r . f ( ; r c i . ; r n c l l ~ t

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IS 337 {) (Part 1) : lOO!)

LAT::R FILLED

-. :.PREPARED JOINTSURFACE

4AFIG. 4 TYPICAL TB-fPORAi(Y OrEN JOINTS

iI'JITI,c..L GAPLATER. FILLEDI/VITH CONCRETE

JOINT SEALING~ " - -COMPOUND48

Where measures are taken for example, by the inclusionof suitable jointing materials to maintain the watertightness of the concrete subsequent'to the filling ofjoint, this type of joints may be regarded as beingequivalent to a contraction (partial Of complete) asdefined above.IQ.2 Design an d Detailing of JointsDesign of a-movement joint should aim at followingdesirable properties for its efficient functioning:

a) The joint should accommoda'te repeatedmovement of the structure without loss ofwater tightness.

b) The design should provide fO f exclusion ofgrit and debris which would prevent theclosing of the joint.

c) The material used in (he construction of.movement j o i n t ~ should have the followingproperties:1) It should not suffer permanent distortion

or extrusion and should not be displacedby fluid pressure.

2) It should not slump unduly in hot weatheror become brittle in cold weather.

3) It should be insoluble and durable andshould not be affected by exposure toli.ght or by evaporation of solvent orplasticizers.

4) In special cases, the materials should benon-toxic, taintless or resistant tochemical and biological action as may bespecified.

Congestion of reinforcement should be avoided duringdetailing. Various methods such as choosing the

diameter and grade of steel carefully and bundling ofreinforcement, if required, are available.10.3 Spacing of Movement JointsThe provision of movement joints and their spacing:Ire dependent on the design philosophy adopted, thatis, whether to allow for or restrain shrinkage andthermal comraetion in walls and slabs. At one extreme,the designer may exercise control by providing asubst:mtial

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IS 3370 lP"rt J) : 2(109Table 2 ~ c s i g n Option for Control of Thenual Contrncti.onand Restrained Shrinkage

(Clallse 10.3)Option Typeof Construction and !\Iovemcnt Joint Spacing Steel Ratio Comments

Method of Coutrol (see Note 2)( I) (2) (3) (4) (5)

Continuous: for full restraint

Semi-con'!inuolls: fo;partial reslrai:1(

~ ~ o joi,,(s. but expansion joints at wide spacings may be Minimumdesirable in walls and roofs that are not protect.:d from. of Pm,solar II,,;!! gain or where the COnlained liquid is,ubjected (o"asubstantial ICmperature r:lllgCa) C o m r H ~ j ( ) i m s : S 15 m Minimumb} A f ! c - < ~ e r:'::!1i.:li and cumpktc of g.:r i l

j'Jia" \;,) illlap'Jlatio:!): S I 1.25 111c; l'ani:iI joints: s7.5m

Use sma!! size bars atclose spacing 10 avoidhigh steel ratios well inexcess of P

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\:,$" ./.::t .'*.. J... . :. ..' .. . I/J." .'..... ,'. .. '. ....

IS 3370 (Part 1) : 200')prc'p:uc;J surf:lcc 5houlj h: in a -:k.ln ~ a t u r a t c d ,,;uffnecdry cl,r:jition when fr::;,h Cllner,',c: is placed. fi::;uirbl iLIn (he L:

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IS 3370 (Pari 1) : 20\)9structure. In determining jointing materi::lis ducconsideration should be given to the rcquir..:mcnts- ofthe Initial width. These will normally require themaintenance of a certain minimum width of gap duringmaximum expansion of the structure. Thejoint shouldbe suitably treated so as to maintain water-tightnessduring movement of the joint (see Fig..6).10.4:2.3 Sliding jointsThe two concrete faces of a sliding jClint should beplane and smooth.Care should be taken by the lise of a rigid screeningboard or other suitable means to m3ke the top of theiower concrele as flat as possible. TLs surf

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IS 3370 (Part 1) ; 2009

,;O:::T SE/,L!NG rltETp,LLlCr , ~ E T / ' . c . d C v V ; ' , T : : : " : ~ BAR

".CO'-':POU,".)D INATER 8pR

I,--

1--'", J.j .r" . 4.:" I '. 'rj' 4 . ~ ~ : . /, .4,... ,., _ .. ' .,._ '. ... "," . f' .t .. : .:..:r

i ~ ' . ' .\. .... 1: & ~ : g ~ ~ ..--\ : : FILLER

6e 60TWO CO/\T JOiNT SEALING STRIP PAINTING

COMPOUND

..

. c!; ..

PREC/,ST COVER

.' ..... " , " ' . ,"

6E

FlO, 6 TYPICAL DET.AILS SHOWING USE OF JOINTING MATERIALS IN MOVEMENT JOINTS (EXPANSION TYPE)10

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tlie firSl-placcd concrc.le_ 11 can be arp[CCi;HCd,h { ) v " ' c v c r ~ thJt lhe tJSL.' of n t ~ \ l . \ _ ' r n ~ . : . . : ~ t 2 ; - i ~ ~ ~ ; . . rn::L.:sa var ictyo[ shapes or sections. SO::o;;' of tLese d c s i g n ~ , for example, those Wilh se\'cr2.! rcnjcctions (SN Fig.5D). would not nccif 10 be passed through the: t'noshutler and by occupy ing a bigger proportion of thethickness of the joint would also lengthen the sbortesta"tcrnative water path through the concrete,10.5.3 Joil1! Sealing Compound!:]..}inl se;::.!ing c o m p o \ J ; ~ d s :m.' d,;.:tikmaterials which arc required to prdviJt' a water-lightseal by adhesion to the concrete throughuut the lln;;cof joint movements. Th-.: commonh used I11Lllcnal" ,Irehas.:d all aspball. bilUrncn. or co,,: tar pitCil \,jitl or\':ithout fillers, such limestone: or SblC dust, m',oeslOsfibre. chopped hemp. rubber or other suitabk material.These are lIsually applied after construction or justbefore the reservoir is put inliJ $::rvicc by pouring inthe hOl or cold state, by trowel1ing 0; ' gunning or asperformed strips ironed into posi:i,\,l. These may alsobi.'. applied during construction S [ j ~ ' ; , as b ~ , packinground tfle corrugation of a water b;,; A primer is oftenused 10 a,;si,,( adhesion and SCHilc b ~ i . l ,hying u; ' theconcrete surface with the help of a blow Jamp isad v i s ~ l b l e . The leng th of the shortest v.ater pa:h thrpugh

The main difficulties experienced with this class ofma{cri:ll arc in obtaining pcrmant>nt adh6ivn to the

, concrete during movement of the joil1l \',hiisl the-smne time ensuring that the mater!:)] docs n[)1 slumpor i" n01 extruded from the join!.In floor joints, the scaling compound is usually appliedin a chase formed in the surface of the concrete alongthe line of the joint (see Fig.6A). The actual minimumwidth will depend on the known characteristics of thcmaterial. In the case of an expansion joim, the }mver.part of the joint is occupied by a joint filler (seeFig. 6D), 'nlis type of joint is generally quite successfulsince retention of the material is assistcd hy g r ~ y i t y and, in many cases, scaling can be delayed until justbefore the reservoir is put into service so thaI theamount of joint opening subsequently 10 beaccommodated is quite small. The chase should not betoo narrow too deep to hinder complete filling and thelength of the shortest water path Ihrough the concreteon either side of the joinL Here, again a wider jointdemands a smaller percentage distortion in the mall'rial. .An arranigement incorporating a cover slab, similur tothat shown in Fig. 6E, may be advantageous in reducingdependence on the adhesion of the sealing compoundin direct tension.

11

IS 337(: (rar! 1) : 20(1)11 CONSTRUCTlO:t\11.1 Unless otherwise specified in this standard, til(:provisions of IS 456 and IS 1343 shall apply to theconstruction of reinforced concrete and prestressedconcrete liquid retaining structures, respectiyely.1l.2 JointsJoints shali be constructed In accordance withrequirements of If.11.3 Construction of Floor's11,3.1 Ffoors FcrmJed Of ; rhe Ground11.3..1.1 \Vhc,c: v.;Jlls or !i{)c';c ::Irc founded on thl:ground, a layer of kan concrete not less Ihan 75 millthick shall be placed over the ground. In normal'circumstances this t1allaycr oft:oncrctc may be weaker

than thaI used in Olher p2.;1s:Qf the struClUrc. hut notweaker than M 15 as specpied in IS 456. Where,ho\\,{,'vcr injurious soils or aggressive ground water arcexpected. the concrete should not be we"kcf tj]"n M 204 l ~ s p ~ c i f i e J in IS 456, and if n e c e s s a ~ ' ~ - - S U ! p h ~ l t c r

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IS 3370 (Part 1) : 200911.7 Lining of TanksTh e t}'pe of liquid to be stored should bt.: considered in,:-,iation to the possibility of corrosion of the steel or;:![ack 00 the concrete, Provision of an impermeableprotecti'/e lining should be considered for resistanceLv [f:c effects of corrosive liquids. Cert ain natura I watersexhibit corrosive characteristics and in such cases it isimportant to obtain a dense impermeable concrete andwith a higher cement content. An'increast:d cover tothe steel is also desirable. Use of sulphate resistingPortland cement, Portland pozzolana cement, orPortland slag cement may in certain cases beadvantageous.12 TEST OF STRUCTURE12.1 In addition to the structural test of structuresas given in IS 456, tanks shall also be tested forwater-tightness at full supply level as describedin 12.1.1 and 1.2.1.2.),1n addition, the roofs of tanksshould be tested in accordance with 12.1.3.12,1.1 Th e tanks shall be filled .with water and afterthe expiry of seven days after the filling, the level ofthe surface of the water shall be recorded. Th e level of(he W;1h.:r shall be recorded ag:un;:it subsequent intervalsof24 hours over a period of seven days. Th e total dropin surface level over a period of seVt.;n days shall betaken as an indication of the water-tightness of the tank.The actual permissible nature of this drop in the surfacelevel shall be decided by tak.: ng into account I,vhether, ~ , c r;):1t:s :rre ('pen or closed and the correspondingeffect it hc.s on evaporation losses ::mclJor on accountof rainfalL However, underground tanks whose top iscf)vcred ma y be deemed to be water-tight if the totaldrop in the surface level over a period of seven dayscioes not exceed 20 mm .

In case: of tanks WhlbC: -c:\terrlJl faces arl.! exposc;d suchas elevated tanks, thl' :-egu irernents of lh..: tests shall bedeemed to be s3tisfil.'J jf (he external fac..:s silow nusigns of leakage and rc::1uin apparc:otly dry over thep..:riod of observation of seven days aflcr allowing aseven day period for absorption at'tt:r filling.12,1.2 I f the srructu:-e does nut satisfy the conditionsof lest, and the daily drop in water level is decreasing,

' . . the period of test may be extended for further sevendays and if specified limit is then reached, the structuremay be considered as satisfactory.12.1.3 The roofs of liquid-retaining structures shouldbe water-tight and snould be tested on completion byflooding the roof with water to a minimum depth of25 mm for 24 h or if so specified. Wh:::re it isimpracticabk, becau"e of roof slopes or otherwise, [0contain a 25 mm depth of water, the roof should havecontinuous water applied by a hose or sprinkler systemto provide a sheet flow of water over the entire area ofthe roof for not less than 6 h. In either case the roofshould be considered satisfactory if no leaks or damppatches show on the soffit. Should the structure notsatisfy either of these tests then after the completionof the remedial work i! ;:;hould be retested in a c c o r d ~ ; 1 c ' e with this clause. The roof insulation and covering ifany, should be compkWd as soon as possible aftersatisfactory testing.13 LIGHTNING PROTECTIONThe liquid retaining 5trunurcs shall be Piotc(;o.c:dagainst lightning in a c c ~ r d a n c e with IS 2309.14 VENTlLATIDNTh e luinimum required ventilation shall be en:Wfcu.

ANNEXA(Clause 2)

. -'LIST OF REFERRED INDIAN STANDARDSIS No.

455: 1989456: 20001343: 19801489 (Part 1) :

TitleSpecification Jor Portland slagcement (fourth revision)Code of practice for plain andreinforced concrete (fourth revision)Code of practice of prestressedconcrete (first revisioll)Specification for Portland pozzolanacement: Part I Fly ash based (thirdrevisioll)

12

IS No.2309 : 1989

3370 (Part 2) :2009

;11682: 1985

TitleCode of pm;[ice for the protectionof huildings and allied s t r u c ~ u r e s a g a i ~ s t lightningCode of practice for concretestructures fo r storage of liquids:Part 2 Reinforced concrete structures(first revision)Criteria for design of RC C stagingfor overhead water tanks

1991

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IS 3370 (Part 2) : 2009

Indian StandardCONCRETE STRUCTURES FORSTOR_AGE OF_ _ w

LIQlJIDS - CODE OF PRACTICEPART 2 REtNFORCED CONCRETE STRUCTURES

( First Revisipn )1 SCOPE1.1 This standard (Part 2) lays down the requirementsaprl:cable specificalJy to reinforced concrete s1ruc!Urcsfor the siorage of liquids. mainly water. Theserequirements are in addition to the general requirementslaid down in IS 3370 (Part I) .1.2 This s t a n d a ~ d docs not cover the r e q u i r e ~ l e n t s forreinforced and prestressed concrete structures forstorage of bot liquids and liquids of 10\>,' viscosity and!ugh penetrating power like petrol, diesel oil, etc. Thisstandard also does not cover dams, pipes, pipelines,lincJ s t r U G t u r ~ s and damp-proofing of b : , ~ t ' n H ~ l l t s . Speci:.;.] problems of shrinkage arising in the storageof non-aqueous liquid and th e measures necessary\':lie: chemica; utt::ck is possibk arc: also not dealtwith The [ecommendations, hO}"cver, may generallybe applicable to the storage at normal temperatUres ofaqueous liquids and solutions which have nodetrimental action on c o n c r e t ~ and steel or where

3 GENERAL REQUIREMENTSDesign and construction of reinforced concrete liquidre,aining structures sl1:l11 (;'Jmr1y I.IIIl the requirementsof IS 3370 (Part I) and IS 456 unless otherwise laiddown in this standard.4 DESIGN4.1 GeneralProvisions shall be m a d ~ {'Dr cunditions of stresses thatmay occur in accordance with p:inciples mcch:.::::cs,recognized methods of de-sign "nd sound engineeringpractice. In particular, adequate cdnsideration shall heuiven to the effects of monolithic construction in thee .a.ssessment of a.-dal forCe, bc'ndin.;,: moment and shear.4.2 LoadsAn stmcturesrequiredto retain liquids should be designedfor both the full an d empty conditions, and theassumptionsregardirrg t.he a . i T ; m g e ; n ~ n t s ofloJding should

sufficiafH preeatliOft8 I.tre iaken to enStlfe protection-. oe-such as to cause the most crilical effects. For loadof co;;crctc :md STeel from damage due [0 action ofsuch liquids as in the case of scwage.2 REFERENCESTh e following standards contain provisions. whichthrough reference in this text, constitute pro\'isions ofthis standard. At the time of publication, the editionsindicated were valid. All standards are subject torevision an d parties to agreements based'on thisstandard !lre encouraged to investigate the pDssibilityof applying the most recent editions of the standardsindicated below:

IS No.456: 20001786: 2008

(Part 1) : 2009(Part 4) : 1967

TitleCode of practice for plaih andreinforced concrete (fourth revision)Specification for _high strength barsand wires for concrete reinforcement(fourth rel!isiol1)Concrete structures for the storage ofliquids - Code of practice:General r e q u i r ~ m e n t s (first revision)Design tables

combinations, water load S ~ . 1 1 1 b. l ; ( : a , ~ d as Jc:.;d load'.Liquid loads should aliaw for the acw

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4.5.2.2 Smmglh calculationIn s:rcngth calculations, the permissible CO[l(;retestresses shall be in accordance with Table 2 and Table 3.

Table 2 Permissible StTCSSes in Concrete Ail values are in Nimm2

5! Grade of Pennis.ib!e Stress in fCilnissih!eNo. O:.>n.crele Compn:ssior: S t r { ' ~ s ir. H,md(..-\. ver-agc) forPlain n ~ i hiB ~ n d i n g D i f ~ ~ t ~ n S ~ C f l

Gc;. '::'t-:lIJ""(I ) (2) (3) (4) (5);"1 0 i) M2 5 S.5 6.0 " : . Ji!) M30 10,0 S.O LO iii) 1.135 11.5 9.0 !. l i\') ::.140 13.0 10.0 1.2 I\') M45 14.5 I i.O . , . J;\1) M5 0 16.0 12.0 .. ..,

NOT5S1 T h < : ~ ' a l t ! e s of permissible shear stress in concrete are giWfi inT ~ b ! e3.."::rhe bond stress given in co! 5 shaH be ilicrcdsed by 25percent far bars in compression. .3 In case of defOl 1I1ed bars conforming to IS 1786, the bondstresses given above may be increased by 60 r c r c ~ n t Table 3 Permiss ible Shear Stress in CO!"lcrete

( C l a l ~ s e 4.5.2.2, and Tahl 2) S!

No. 100 MPenni$sibte Shc.zr Stress in CO;t{ ret:- 7 ..

l'lmmlGrade of Concreter .-A - ,M25 l\HO MJ5 l\1'..fO ~ ~ ; ; d Ao6\'e

(I ) (2} (3) (" t5) tt,}i) 'S 0.15 0.19 0.20 0.20 0.20ii) 0.25 0.23 0.23 0.23 0.23iii) 0.50 0.31 0.3\ 0.3\ () " .JLiv) 0.75 0.36 0.37 0.37 0.38\") l.OCl 0.'10 0.'11 0.42 0,-12vi) 1.25 0.44 0.45 0.45 OA6\'ii) 1.50 0.46 0.'18 0,49 0,49viii) 1.75 0.49 0.50 052 0.52IX) 2.00 0.51 0.53 0.54 0.55x) 2.25 0.53 0.55 ( ) . 5 ~ 0.57xi) 2.50 0.55 0.57 0.5& 0.6Dxii) 2.75 0.56 0.58 0.60 0.62xiii) :tOO and 0.57 0.60 0.61 0.63above

NOTE A. is that area of longitudinal tension reinforcemen:which continues at least one effective depth beyond the sectionbeing cunsidered except at suppot1S wheie the fnll area oftension reinforcement may be used provide.:! the deiallingconforms 1026.2.2 and 2G.2.3 oflS 456.4.5.3 Permissible Stresses in Steel4.5.3.1 Resistance to crackingThe tensile stress in the steel will nccessarily be Iirniltdby the that the permissible tcnsile s ! r c : o ~ ir. t l ~ e concrete is not ex.ceeded: so the tensile strc:.iS in

IS 3370 (P!]rt 2) : 2009stetl sh:.!ll be cquallO thes t e " c . ~ ariG t . " . ~ : : ~ r e t e 1 Jild the of modular ratio of(""","cc""c,",,,,\1'1tensile: stress in concrctc_4.5.3.2 Srrens/II calcnlntiOl'sFor strength calculalions, the permissible stresses insteel shaH conform to the values specified in T ~ b l e 4.

Tahle 4 Permissible Stresses in Steel

51r\Ct.

l)"f1c of stress in S t ~ c 1 Reinforcement . l'crmissitdc Stresses, N/nim'l, _____..A. """P!3ifi RoundMiid Slcei Bars E.igh S t r l ! n ~ t h D e f o r m ~ d 13 ars

( i) (2) (3) (4)i) Tensile Stress in mcmbcos 115 130 vunder direc[ tenslnn,

~ n d i n g and shearii) Compressive 51feSS in i 25cohlmns s l 1 b j e c t ~ d to

d ! r ~ c t !o3d

4.5.4 Stresses Due to Moisrure or TemDeratltre C/uwgpsr{o s e p ~ 1 r H : 2 calculation i;; required fur stress.esdl:e tomoisture or temperature c!iznge in the concreteprovided that:

a) The reinforce.ment provided is not less tilanthat specified in 8,

oj The re.commendat!orrs of the standard withregard to the provision ofaqd for a suitable siiding layer beneath theta;1k given in IS 3370 (Part 1) are ; ; ; ~ 1 p i i c d with,

c} The tank is to be USed only fo r the storage ofwater or aqueous liquids at or near ambienttemperature and the concrete never dries out,and ,(

d) Adequate precautions are taken to avoidcracking of the concrete dur"ing th econstruction period ami until the tank is putinto use.

4.5.4.1 ShrinkHge stresse.s may, however, be requiredto be calculnted in specicJ cases. when a shrinkagecoefficient of 300 x 10.6 may be assumed.4.5.4.2 Where reservoirs are protected with aninteniai impermeable liniMg, eonsidenltion shouldhe given to the possibiiity of c o ~ c r c i . e eventually,drying out. Unless it is established on the basis oftests or experience that the lining ha s adequate crac-kbridging p r o p e . r t 1 e s ~ alID\\'3nce for the ir:creasedeffect of drying shrinkage should be made in the

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inf;u..:n.:c (;[liquid p:-cssurc iSfCSlrictcd at theb ~ l ~ e .

b) Unless I h ~ extent .: rossihiiiiy of sympathetic cracking, it isimportant [.) C I l S l J r ' , ~ thaI movement joints in the roofcOITc:spond with rh,)sc in walls j f roof and walls aremoni!ithic. Jr. however, provision is made by meansof a sliding joint fo:' movem

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.. . (2 )\vhcre

. f h 'I " t 'tJUlO 0 : .e[ensl e strength 01 the concrete= ~ , ) 10 the average bond s t r ~ n g t l : betweenconcrete and steel,

(.'\ sizc_of each reinforcing bar, andp =steel ratio based on th e gross concrdese.ctiOl! .

For inlIltature concre[c., {he vatue (I f , J ~ inay he t ~ 1 k c n Jcas unity for plain round bars and 213 for deformed bars.

Th e above formula may be expressed for designpurposes as:2bDx-- . ,.(3)fb J'tsM"x

whereJib number of h ~ r s in width of section.b = width of seclion;D overall Jcp!h of member, andS M " ~ ; : ; : obtained from \'1M",.

The widlh of a lully Je ,-eloped eke/'; duv l.[ax ;:;: estimated likely maximum crack spacing,c> estimated shrinkage strain, and= estimated total thermal contraction after

peak temperature due to heat of hydration.For immature concrete the effecti \'e coefficicI1l ofthenml contraction may be taken as one haif of thevalue for mature conCrete (due to the high c reep straillin immature concrete).For walls exposed to normal climatic conditions theshrinkage strain less the associated creep strain isgenerally less than the ultimate concrete tensile'strainof about 100 x 10.6 ~ n l c s s high shrinkage aggregatesare used. Hence the yaluc of WMa: for cooling 10ambient from the peal: hydration temperature may beassumed Lo be:

.. . (5)

is 337(1 (Part 2) : 2009

coefiici-:IH of thernlal e.xranslo:1 of Iuatufcconcrete, and

T, ::: fan in temperature be.tween the hydrationpeak and ambient. '

Tbe value of TI depends on the temperature ofconcrelim:, cemen!contenL thickness 'Of the memberand m a t ~ r i a l for"shutters. As guideline, it isr e c o m r i . 1 \ ~ l l d e d 10 us'c TJ = 30C for concreting. inSU:'l1!11er and 20-:'C for c O i i ~ ' r C ' < t i n g during \4 . ' i n ~ e r , \.--hcnsled ;,;huHers arc used. For other condition ;;, the valueof T1 may be appwpr imcly incrl!ased. In adJililil) W the lCmp(Oraturc fall TI' there can be a further fali in temperamre, Tzoue [() S;;'.,iSOf1:li variations. The consequent thermal contractions OCCUi in the mature concrete fo r which th e factors controlling cracking bebaviour are subsianti::lly modified. The raiio of l h ~

" Ie: .ilcnSile strength of concrete to bond strength, -, l !fcappreciably lower for mature concrete. In addition, therestraint along the base of the member tends to be muchr i i ~ ' , ; ' ; , ; uniforni and less susccpiihk: to Sln.!ss r : . l l ~ ; ; r s 1 sinceli considerable shear resistance can be dcvdoped alongthe- entire ! ~ n g t h of the construction joint..A.L.bOl.:gl1 pr(',ci::.t J ~ : ; . t arc not 3 \ : ~ " i i l : l b l ~ for itie cff\,;:..:.sc r e [ : s o n ~ 1 h j e . c:;tin1atc 1113Y he .assun1cd that {hecO!llbined effect of these factors is to reduce theestimaled contraction by half. Hence the value of \ r ~ l J ' when taking an additional seasonal ten)per:Hure fall-into account is g i o , ~ ' ~ ~ ~

a ( .H'Max = SM"" X 2 x r. +T,,) ., . (6)When movement joints are provided at not more than15 II I centr es, the subsequent temperature fail; T2, neednOI be. considered. ,A-2 THICK SECTIONSFor 'thick' sections, major ci'luses of cracking are thedifferences which develop between the surfaee zonesand the core of the section. The thickness of concretewhich can be considered to be within the 'surface zone'is somewhat arbitrary. However, site observations haveindicated thaI the zone thicknesses for D > 500 mm inPig. 1 and Fig. 2 are appropriate for thick sections,and the procedure for calculating thermal crack controli e 1 n f o r c e ~ i e n t ' i n thick sections is same as that for thinsections.Th,:: maximum temperature rise due to heat ofhydretionto be considered should be the average value for the entirewidth of section. The temperature rise to be consideredfor the core should be at Ie:,,,!] C!'C higher than the vahlewhich would be assumed for lhe entire section.

7

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IS 3370 {Part 2) : 20092h ! ) hI = width of the seCtion at the centroid of theE:;= t .. (11) tension steel,3E,A, D = overall depth of the member,. Fur a limiting design surface crack width 0[0.1 mOl: E.::: modulus of elasticity of reinforceme.nt, and

As = area of tension reinforcement.b,D.; =-- - .. . (12)- E,/l, TI1e stiffening effect factors should not be interpolatedor extrapolated and apply only for the crack widthsE2 ::: stmin due to stiffening effect; Slated.

ANNEXC'(Foreword)

COMMIITEE CO.r.lPOSITIONCement and Concrete Sectional Committee:- CED 2

ttOrganizaTion R e p r e s e n l l I t i l " l ~ ( s ) [);1I1i TOllrism and Trnnsportaliun Development Corporation SHru JOSE KURIAN (Chairma;:)

Ltd. New DdbiACC Ltd. Ml1Jllon.! SHRI NAVEEN CHADHA

SI-'.Kl P. S = 1 V A . ~ " : - : (AITN/Wld. Atomic Energy Regulatory Board, Mumb