Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. इंटरनेट मानक “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “प0रा1 को छोड न’ 5 तरफ” Jawaharlal Nehru “Step Out From the Old to the New” “जान1 का अ+धकार, जी1 का अ+धकार” Mazdoor Kisan Shakti Sangathan “The Right to Information, The Right to Live” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 3370-4 (1967): Code of practice for concrete structures for the storage of liquids, Part 4: Design tables [CED 2: Cement and Concrete]
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Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.
इंटरनेट मानक
“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru
“Step Out From the Old to the New”
“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan
“The Right to Information, The Right to Live”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
“Invent a New India Using Knowledge”
है”ह”ह
IS 3370-4 (1967): Code of practice for concrete structuresfor the storage of liquids, Part 4: Design tables [CED 2:Cement and Concrete]
IS : 3370 (Part IV) -1967(Reaffirmed 2008)
Indian StandardCODE OF PRACTICE FOR CONCRETE
STRUTURES FOR THE STORAGE OF LIQUIDS
PART IV DESIGN TABLES
Fifteenth Reprint AUGUST 2007(Incorporating Amendment No. 1 & 2)
STRUCTURES FOR THB STORAGE OF LIQUIDSPAIlT IV DESIGN TABLES
Cement and Concrete Sectional Committee, BDO 2
C}u,irma"SRRI K. K. NAMBIAfC
R."."'i,,.The Concrete Association of India, Bombay
}\·I. N. Dastur & (4 (Pvt) Ltd. CalcuttaSahu Cement Service, New DelhiBhakrn & Beas Design. Organization, New DelhiCentral Uuilding Research Institute (CSIR).
Roorkee
AI;".6"sSRRl M. A. MEliTA (Allemtlt, to
Sbri K. K. Nambiar)SRat K. F. ANTIASRRI A. P. BAGeHtSHIU P. S. "HA1·NAOAR1). S. K. CHOPRA
The A!lsociated Cement Companit'l Ltd, Bombay
( CSIR),In.tituteS. B. Joshi It Co Ltd, BombayCentral Road Rrleareb
New Delhi
SHRI J. S. SJlARMA ( Alt,rnlll, )DtRsCTOR (CSl\{) (~nll2111Natt.'r& Power r..ommi.sion
DIRKCTOR ( DAMS III ) ( AlIt,,,al, )DR R. K. OIlOSH . Indian Road, Congress. New DelhiSR.I B. K. GUllA Central Publtc \Vorks Department
SUP.RINTENDING ENQJNif.R, 2ND
OJ.CLI. ( Alt""." )na R. R. HATrIANOADISRRI V. N. PAl ( Altn~.', )
JOINT DIRECTOR STANDARDS R~.e.rc:h, ~sjgnl at Standareb . Orluization( B I: S ) . ( Ministry of Railways)
DuUTY Dr.aero. STANDARDS( B &: S) (.4llnllll'.)
SR.I S. B. JOIHI .,.PRoP S. R. MaRRA
DR R. K. GHOIH ( AI,,,,,tllI )SRal S. N. Muu.aJI National Tnt Houle, Calcutta8..-. B. K. RAMCHANDR'AN (Allmual. )S... BaACH A. NADlasHAH Institute of EDlineen ( India ), CalcuttaBalo NAUlH PRASAD Enlineer-in·Chi~r·. Branch. Army HeadquarlenSRal C. B. PAT&L National Buildings Orpnization
SRa. RA8IMDU SINOH ( Al'mwd, )SHall. L. PAUL Dirtttorate Gen~ral ofSuppliei • DiapGlallS.a. T. N. S. IlAO Gammon India Ltd. Bombay
S... S. R. PacHltlaO ( If"."..,. )RaPaaaTAftva GeoloRical Surveyor India. CalcuttaRa•••aNTAn.. The India Cementl Ltd, MaclruS.al K. G. SALVI HiDdustan HoUlin, PactO!'J Ltd, New Delhi
SHaJ C. L. KAiLlWAL ( .41'""", ) (c.littMI.,.,. 2 )
BUltEAU OF INDIAN STANDARDSMANAK BHAVAN~ 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
IIISS7I ( Part IV ) • 1967
( CortIiuMlft-,." I')M.ahrs ..
D.S. SARKA.Ill".",..,
Structural EOlineerinl Rae.rch Centre (CSla.).Roorkee
S.1It1 Z. Gaoao& ( AI"""",)SaCUTAIlY Ceatral Board of Irrilation .. Power, ~ew DeIhlSHRI L. SWAaoop Dalmia Cement ( Dharat ) Ltd, New Delhi
SHill A. V. RAIIANA (AI""..,.)SIIRI J. M. 1....RAN Roads Wing, Ministry of Transport
SRR' N. H. KUWANI ( .AI,.".." )Da H. C. VJlVaVAIlAYA Cement Research Institute or India, New DelhiSHRJ R. NAGARAJAN, Director General, lSI (Ea-oJfirio M""IJI,)
Directott (Civ Baal)81"".'7
SHR. Y. R. TANaJADeputy Director (Civ Engg) J lSI
Concrete Subcommittee, BDC 2: 2
National Buitdinli Organization
M. N. Dutur It Co ( Pvc) Ltd, Calcutta
s.B. Joshi at Co I..td, Bombay
Hydt'rabad Engineering Research LaboratoryH)'derabad
Dlaacroa·IN"CHARO& Geological Survey of India, LucknowSHU V. N. 'CUNAJI Public \Vorks ~partmcDt, .MaharuhtraSR.I V. K. GUPTA Enginr.cr.in-CbieC·s Branch, Army HeadquartenSIUlI K. K. N'.1lOIIAR The Oonerete Association of India, Bombay
SRRI C. L. N. IVUfOAR (A.lt.,ntl")DR M. L. 'PURl , Central Road Research Inltitute ( CSIR ),
Roorkec-Structural Engineering Research Centre (OSIR.),
Roorkee
Sahu Cement Service) New DelhiIn penonal capacity ( M-60 Cru,ow S." s..69)Central' Building Rete.reb IDititute (CSIR)
RoorkeeDa I. C. Dol M. PAil CUODOU Central Water It Power Commiaion
Dta&CTOR ( DAMS I ) ( Alima." )D&PUT~ DUtECToa STANDARDS Research, Design. and Standards Organiation
( B a. S) ( Mini.try of Railway.)ASSIITANT DIRECTOR STANDAltDl
( BitS) ( AIle,.,..', )D••aCTOR
1-.0' G. S. RAMASWAMY"
c.,.,rSURI S. B. JOIHe
Mltr.bnsSURI B. D. AHUJA
SRRI P. C. JAIN (AI"",,,,,)SRal K. F. AlmA
SHa, B. C. PATEL ( AI,."..", )'SHRI A. P. BAacR;SHRr B. K. eHOKIIDR S. K. CHO••A
Da S. SARKAR ( All,",,,,, )SHa. 'r, N. S. RA.o Gammon India Ltd, Bombay
SHaI S. R. PlNII&laO l.mllmal, )SUP&....TIUfDINO ENGJM&&R, 2ND Central Public Works Department
CulCLESRRI S. G. VAiDYA (AI"""")
SHRIJ. M. TRRHAN R.oads Win., MiDistry orTranaportSHIll R~ P. SI&KA ( AI"",,,,, Jn. H. C. VaVUYAIlAYA Cement Jleaearch Institute ollDdia, New Delhi
2
IS I 3378( Pan IV ) • 1117
Indian StandardCODE OF PRACTICE FOR CONCRETE
STRUCTURES FOR THE STORAGE OF LIQUIDSPART IV DESIGN TABLES
o. FOREWORD
0.1 This Indian Standard ( Part IV ) was adopted by the Indian StandardsInstitution on 7 December 1967, after the draft finalized by the Cement.md Concrete Sectional Committee had been approved by the Civil Engleucering Division Council.
0.2 The need Cor a code covering the design and construction of reinforcedconcrete and prestressed concrete structures for the storage of liquids hd\
been long felt in this country. So far, such structures have been designed tovarying standards adapted from the recommendations of the Institution ofCivil Engineers and of the Portland Cement Association with the resultthat the resultant structures cannot be guaranteed to possess a uniformsafety margin and dependability. Moreover, the design and constructionmethods in reinforced concrete and prestressed concrete are influenced OVthe prevailmg construction practices, the physical properties of the materialsand the climatic conditions. The need was. therefore, felt to lay downuniform requirements of structures for the storage of liquids givinR dueconsideration to these factors. In order to fulfil this need, formulationof this Indian Standard code of practice for cor-crete structures for thestorage of liquids ( IS : 3370) was undertaken. This part deals with designtables for rectangular and cylindrical concrete structures for stor~p'(; ofliquids. The other parts of the code are the following:
Part I General requirementsP....t II Reinforced concrete structuresPart III Prestressed concrete structures
0.3 The object of the design tables covered in this part is mainly to presentdata for ready reference of designers and as an aid to speedy design calculalions. The designer i", however, free to adopt any method of design depending upon his own discretion and judgement provided the requirementsregarding Parts I to III of IS : 3370 are complied with and the structuraladequacy and !afety are ensured.
0.3.1 Tables relating to design of rectangular as well as cylindrical tankshave bern given and by proper combination of various tables it may bepossible to design different types of tanks involving many sets of conditionsfor rectangular and cylindrical containers built in or on ground.
3
II, __ ( Itut IV). 1117
1.'.2 Some of the data presented for d~ip of rectangular tankamay beused for design of some of the earth retaining structures subject to earthpressure for which a hydrostatic type of loading may be substituted in thedesign calculations. The data for rectangular tanks may alia be applied todesign of circular reservoirs of large diameter in which the lateral stabilitydepends on the action of counterforts built integrally with the wall.
0.4 While the common methods of design and construction have beencovered in this code, design of structures of special forms or in unusualcircumstances should be left to the judgement of the engineer and in suchcases special systems of design and construction may be permitted on production of satisfactory evidence regarding their adequacy and safety byanalysis or test or by both.
0.5 In this standard it has been assumed that the design of liquid retainingstructures, whether of plain, reinforced or prestressed concrete is entrustedto a qualified engineer and that the execution of the work is carried outunder the direction of an experienced supervisor.
0.6 All requirements of 18:456·1964· and IS: 1343.1960t, in so far asthey apply, shall be deemed to form part of this code except where otherwise laid down in this code.
0.7 The" Sectional Committee responsible for the preparation of this standardhas taken into consideration the views of engineers and technologistsand has related the standard to the practices followed in the country in thisfield. Due weightage has also been given to the need for intertlational coordination among the standards prevailing ill" different countries of thflworld. These considerations led the Sectional Committee to derive'auistanC'(,:from published materials of the following organizations:
British Standards Institution;Institution of Civil Engineers, London; andPortland Cement Association, Chicago, USA.
~les have been reproduced from C Rectangular Concrete Tanks J
and C Circular Concrete Tanks without Prestressing' by courtesy of PortlandCement Assr.'ciati"n, USA.
0.8 For the purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculated, expressingthe result" of a test or analysis, shan be rounded off in accordance withIS: ~.1960t. The number of significant places retained in the roundedoff value should be the same as that of the specified value in this standard.
·Code or practice for plaia and reinror,ced concrete ($"0,,11 "v;l;on ).tCaclc ofpracticeCot prntraled concrete.~Rulet for rcNndi.."off numerical valua ( "PisItI ).
4
1113370 (Pan IV )-1117
1. ICOPB
1.1 This standard ( Part IV ) recommends design tables, which are intendedal an aid for the design of reinforced or prestressed concrete structure. forstorage of liquid.
2. RECTANGULAR TANKS
2.1 Momeat Coetlldeats for IacUvld••1 wan Pa.el. - Momentcoefficients for individual panels considered fixed along vertical edges buthaving different edge conditions at top and bottom are given in Tabla Ito 3. In arriving at these moments, the slabs have been assumed to actas thin plates under the various edge conditions indicated below:
Table 1 Top hinged, bottom hingedTable 2 Top Cree, bottom hingedTable 3 Top free, bottom fixed
2.1.1 Conditions in Table 3 are applicable to cases in which wall slab,counterfort and base slab are all built integrally.
2.1.2 Moment coefficients for uniform load on rectangular plates hingedat all four sides are given in Table 4. This table may be found useful indesigning cover slabs and bottom slabs for rectangular tanks with one cell.If the cover slab is made continuous over intermediate supports, the designmay be made in accordance with procedure for slabs supported on four,ides ( s" Appendix C of IS : 456-1964· ).
2.2 M.lDeat Coe.deat. lor Rect••plar T••k. - The coefficientsfor individual panels with fixed side edges apply without modification tocontinuous walls provided there is no rotation about the vertical edges. Ina square tank, therefore, moment coefficients may be taken direct fromTables I to 3. In a rectangular tank, however. an adjustment has to bemade in a manner similar to the modification of fixed end moments in aframe analysed by tile method of moment distribution. In this procedurethe common side edge of two adjacent panels is first considered artificiallyrestrained so that JUtrotation can take place about the edge. Fixed edgemoments taken from Tables 1, 2 or 3 are usually dissimilar in adjacentpanels and the differences, which correspond to unbalanced moments, tendto ratat!: the edge. When the artificial restraint is removed they will induceadditional moments in the panels. The final end moments may be obtainedby adding fnduced moments and the fixed end moment, at the edge. Thesefinal end moments should be identical on either side of the common edge.
2.2.1 The application of moment distribution to the case of co'ntinuoUitank walls is not al simple as that of the framed structures, because in the
~ -Code or practice Cor plain aDd reinforced r.ODcrete ( .'..4 MJiliM).
11.117I ( Part IV ). IN7
fonDer case the moments should be distributed simultan~oully all alongthe entire length of the side edge so "that moments become equal at bothsides at any point of the edge. A simplified approximation would be di...tribution of moments at five-points, namely, the quarter-points, the midpoint and the bottom, The end moments in the two intersecting slabsmay be made identical at these five-points and moments at interior pointsadjusted accordingly.
2.2.1.1 The moment coefficients computed in the manner described aretabulated in Tables 5 and 6 for top and bottom edge conditions as shownfor single-cell tanks with a large number of ratios of b]« and cla, b beingthe' larger and c the smaller of the horizontal tank dimensions.
2.2.2 Wh('n a tank is built underground, the walls should be investigatedfor both internal and external pressure. This may be due to earth pressureor to a combination of earth and ground water pressure. Tables 1 to 6may be applied in the case of pressure from either side but the signs willbe opposite. In the case of external pressure, the actual load distributionmay not necessarily be triangular, as assumed in Tables 1 to 6. For example, in case of a tank built below ground with earth covering the roof slab,there will be a trapezoidal distribution of lateral earth pressure on the walls.In this case it gives a fairly good approximation to substitute a trian,le withsame area as the trapezoid representing the actual load distribution.The intensity of load is the same at mid-depth in both cases, and when thewall is supported at both top and bottom edge, the discrepancy between thethe triangle and the trapezoid will have relatively little effect at and nearthe supported edges. Alternatively, to be more accurate, the coefficientsor moments and forces for rectangular and triangular distribution ofload may be added to get the final results.
2.3 Shear CoeSdeDt. - The values of shear force along the edge of •tank wall would be required for investigation of diagonal tension and bondatreIIeI. Along vertical edga, the ahear in one wall will cauae axial ten.ionin the adjacent wall and should be combined with the bending momentfor the purpose oC determining the tensile reinforcement. ~
2.1.1 Shear coefficients for a wan panel ( of width 6, height CI and subjected to hydrostatic pressure due to • HCJuid of density rD ) considered fisedat the two vertical edges and usumed &Inged at top and bottom edges arepftD in Fig. 1 and Table 7.
2.1.2 Shear coefficients for the lame wall ~el considered fixed at t~etwo vertical edges and auumed hinged at the bottom but free at top edgeare pven in Fig. 2 and Table 8.
2.s.s It would be evident &omTable 7, that the difFerence between theshear Cor 6/. - 2 and in8Dity DSO 11II&11 that there is no neceaity Cor computing coeflicients for intermediate values. When bJd is large, a verticalstrip ofthe slab near the mid-point orthe b.dimenuon will behave eesentially
6
IS : 3370 ( Part IV ) • 11&7
as a simply supported one-way slab. The total pressure on a strip of unitheight is 0·5 wa' ofwhich two-thirds, or 0·33 wat is the reaction at the bottomsupport and one-thirds, or 0·17 wall, is the reaction at the top. It may beseen from Table 17 that the shear at mid-point of the bottom edre is0-329 wat for bla == 2-0, the coefficient being very close to that of1/3 for infinity. In other words, the maximum bottom shear is practically constant for all values of b]« greater than 2. This is correct onlywhen the top edge is supported, not when it is free.
2.3.3.1 At the corner the shear at the bottom edge is negative and isnumerically greater than the shear at the mid-point- The change fromposrtive to negative shear occurs approximately at the outer tenth-pointsof the bottom edge. These high negative values at the corners arise from thefact that deforrnations in the planes of the supporting slabs arc neglectedin the basic equations and arc, therefore, of only theoretical significance.These shears may be disregarded for checking shear and bond stresses.
TOP HINGED~
~ ~~ ~I--~ 1 I t III1 ~ ~""
~ ~~~ ... ~ 1t.. Ii I,
'I..,-.- i
....b/a =INfiNITY~1'\1 't~~~
t--~~~ ~ , t'
I l'~ ~~-,
~~"- I~~~/a :2 ~ ~"'~ ~, ~,~ b/• • 1..J ~~~ ~
~~&I ~lI ~
~p-. ~~. ~r-.
G: '''b/a If 1/2 ~~ ~~ "'~ I"l
~, ~
~~ ~~~~
~
~,~ ~~
~ ~~
~~~ ~~~~j;i
"'~l.~~.-~ !! jill~
i-li 'J
..~ IJ'i~~~~9~ i~~?'~
0-2
0-9
1-0o 0-1 0-2 0-3 0-4
&HEAR PER UNIT LENGTH : COEFFICIENT x 'Ill.. _ hei,ht or the wall
, - width of the wall., _ density of the liquid causinl hydrostatic pressure
FlO. COBPPICIItNTI '"OR WALL PANEL, FIXBD AT' Va.TICAL Eooa.,HINOED AT Top AND BOTTOM EOOE5' · .
e-
o
7
II.U70 ( Pan IV ) .1117
TOP FREE
~"- ~~ "'~~'"
"-,.. 1111'1
~ ~ ~lIlI "'~Ill. 'J~b/••3~ ~"- ,...~ ~~,
r--~ ~~ "- ~"--.
~ ~. --~Ilrt. b/•• 2~~
llilI~~~
----,~~
.,t-.~ ~~ ~~
4b/•• 1 ~~ "'It.~ f ~
~~r--
~
~~fa ~~ ~ "~tS J,' · I ,~ ~~ ~
~u.
~t/••1/2 ~
,!Ill ~
, ,~ ~
\ ~ ~~
,~
~~,
~.J ......
---~~ ~
~ .. ",'" ~.•• ~~~'R~rpr, r~~~
01
o
1·0o 0-1 0-2 0-3 0e4SHEAR PER UNIT LENGTH • COEFFicIENT • • 1
• - beiabt of the: wallII - width 01 the wallIII - demity 01the liquid cauaing hydroltatic prasure
FlO. 2 eo.PftCJ&IITI 1'0R WALL PANBLt FIXBD AT Va.TICAL Eoo..,HINGED AT Bonoy EDO~ AND FREB AT Top EDGZ
2.3.3.2 The unit shears at the fixed edge in Table 7 have been usedfor plotting the curves in Fig. 1. It would be seen that there is practicallyno change in the shear curves beyond b[a== 2-0. The maximum value occunat a depth below the top somewhere between 0-6a and 0-&. Fig. 1 will befound useful for determination oCshear or axial tension for any ratio of /Jlaand at any point of a fixed side edge.
2.3.4 The total shear from top to bottom of one fixed edge in Table 7should be equal to the area within the correspondmg curve in Fig. 1. Thetotal shean computed and tabulated for hinged top may be used in makingcertain adjustments 10 as to determine approximate values of shear for wallswith free top. These are given in Table 8.
2.3.4.1 For /Jla fID l /2 in Table 7, total.shear at the top edge is so smallal to be practically zero, and for bla-I·O the total shear, 0·005 2, is onlyone percent of the total hydrostatic pressure, o-SO. Therefore, it wouldbe reasonable to assume that removing the top support will not Dl&tcriallychange the totallpean at any of the other three edges when IJ/.-1/2 and I.
S
III 3370 ( Part IV ) • 1967
At 6/1'-2-0 there isa substantial shear at the top edge when hinged, 0-053 8,so that the sum of the total shears on the other three sides is only 0-44 62.If the top support is removed, the other three sides should carry a total of0-50_ A reasonable adjustment would be to multiply each of the threeremaining total shears by 0-50/0-4462==1-12, an increase of 12 percent.This has been done in preparing Table 8 for 6/0-2-0_ A similar adjustmenthal been made for 6/a=t3·0 in which case the increase is 22 percent,
2.3.5 The total shears recorded in Table 8 have been used for determination ofunit shears which are also recorded in Table 8. Considering the shearcurves in Fig, 1 and assuming that the top is changed from hinged to free,for lIia=! and I, it would make little difference in the total shear, that is,in the area within the shear curves, whether the top is supported or not.Consequently, the curves for bjac=l and 1 remain practically unchanged.For 6/(,1==2 an adjustment has become necessary for the case with top free.A change in the support at the top has little effect upon the shear at thebottom of the fixed edge. Consequently, the curves in Fig. 1 and 2 arenearly identical at the bottom. Gradually, as the top is approached thecurves Cor the free top deviate more and more from those for the hingedtop as indicated in Fig. 2. By trial, the curve for b/a=2 has been so adjusted that the area within it equals the total shear for one fixed edge for6/.-2-0 in Table 8. A similar adjustment has been made for 6/G==3-0which is the limit for which moment coefficients are given.
2.3.5.1 Comparison of Fig_ 1 and Fig. 2 would show that whereasfor IJ/a ss2'Oand 3·0 the total shear is increased 12 and 22 percent respectivelywhen the top is free instead of hinged, the maximum shear is increased butslightly, 2 percent at the most. The reason for this is that most of the increase in shear is near the top where the shears are relatively slDall.
2.3.5.2 The same procedure has been applied, for adjustment of unitshear at mid-point of the bottom, but in this case the greatest change resuIting from making the top free is at the mid-point where the shetar is largefor the hinged top condition. For example, for 6/(1=-3-0, the unit shearat mid-point of the bottom is 0-33 wal with hinged top but 0·45 Will withfree top. an increase of approximately one-third.
2.3.6 Although the shear coefficients given in Tables 7 and 8 are forwall panels with fixed vertical edges, the coefficients may be applied withsatisfactorv results to any ordinary tank wall, even if the vertical edges arenot fully fixed.
3. CYUNDRICAL TANKS
3.1 RID. Tea.loa .Dd Momeat. I. Wall.
3.1.1 WQIl with Fi:cld Bas' alld Free Top, Subject,d ItI 'Irian..Il"lor Loa«( Fi,. 3 ) - Walls built continuous with their footings arc sometime d~~iJtnf'cl
as though the base was fixed and the top free, although ~tri(·tJy ~p«,akinJ·
9
IS I 3370 ( Pan IV ) • 1967
the base is seldom fixed) but it is helpful to start with this assumption andthen to go on to the design procedures for other more correct conditions.Ring tensions at various heights of walls oC cylindrical tanks fixed at base,free at top, and subjected to triangular load are given in Table 9.lvloments in cylindrical wall fixed at base, free at tcp and subjected totriangular load are given in Table 10. Coefficients for shear at base ofcylindrical wall are given in Table II.
FlO. 3 WALL WITH FIXED BAsa AND FREE Top SUBJECTBDTO TltlANOULAR LOAD
3.1.2 Wall ,oi," Hinged Bas« and Fre« Top, Su6jteted 10 Triangular Load( Fig. 4 ) - The values given in 3.1.1 are based on the assumption that thebase Joint is continuous and the footin, is prevented from even the smallestrotation of kind shown exaggerated In Fig. 4. The rotation required toreduce the fixed base moment from lome de6nite val~ to, say, zero i. muchsmaller than rotations that may occur when normal settlement takes placein subgrade. It may be difficult to predict the behaviour or the subgradeand its effect upon the restraint at the base, but it is more reasonable toassume that the bale is hinged than &xed, and the hinged-based assumptiongives a safer design. Ring tensions. and moments at different heights orwall or cylindrical tank are liven in Tables 12 and 13 respective1r.. Coefficients fOr shear at base or cylindrical wall are given in Table 1 •
FlO. 4 WALL WITB HDlO&D BAIS AND Fa.B Top SUBJBCT&D TOTRIANGULAR LoAD
10
U I 3370 ( Part IV ) • 1967
3.1.2.1 The actual condition of restraint at a wall footing as in Fig. 3and 4 is between fixed and hinged, but probably closer to hinged. The comparison of ring tension and moments in cylindrical walls with the end conditions in 3.1.1 and 3.1.2 shows that assuming the base hinged lives conservative although not wasteful design, and this assumption is, therefore,generally recommended, Nominal vertical reinrorcement in the insidecurtain lapped with short dowels across the bue joinIS will 8uif"tee.
This condition is considered satisfactory for open-top ranks with wallfootings that are not continuous with the tank bottom, except that allowanceshould usually be made for a radial displacement or the footing. Such adisplacement is discussed in 3.1.5. If the wall is made continuous ttt topor base. or at both, the continuity..should also be considered. 'These conditions are given. in 3.1.6.
3.1.3 Wall wilh Hingtd Base ontl Fret Top, Subjttlld 10 Trapezoidal Load( Fig. 5 ) - In tank used for storage of liquids subjected to vapour pressureand also in cases where liquid surface may rise considerably a.bove the topof the wall, as may accidently happen in case of underground tanks) thepressure on tank walls is a combination of the triangular hydrostatic pressure plus unifonnly distributed loading. This combined pressure willhave a trapezoidal distribution as shown in Fig. 5, \vhich only representsthe loading condition, without considering the effect of roof which is discussed in 3.1.4. In this case, the coefficients for ring' tension l"ftay be takenfrom Tables 12 and 1(~. Coefficients for shear at the base ere given inTable 11. Coefficients for moments per unit width are given in Table 13.
Fro. 5 WALL WITB HmGED BASE AND FREB Top SUBJECTED·TO TRAPEZOIDAL LOAD
'.1.4 Wall wi'" S. APllied at Top (Fig. 6 ) - ~'hen the top of thecylindrical wall is dowelled to the roof slab, it may hot be. able to movefreely as assumed in 3.1.1 to. 3.1.3..W~en displacement is prev~tedJ !hetop cannot expand and the nng tension IS zero at top. rf T kg IS the ringtension at 0·0 H when the top is free to expand as in 3.1.3, the. value ofshcarY can .be found from Table .15 as bdow:
f'RT== -~H or
11
~ I II" ( Pan .IV ) • 1117
Y NT--x;-where
• - the coefficient obtained from Table 15 depending upon
h · HIt erauom
FlO. 6 WALL WITH SHaAR ApPLIBD AT Top
3.1.5 JVal1 with Shear Applied at Btu« - Data given in Table 15 mayalso be approximately applied in cases where shear is at the base of thewall, ~ in Fig. 7J which illustrates a case in which the base of the wall isdisplaced radially by application of a horizontal shear Y having an inwMI'ddirection. Wh~n the base is hinged, the displacement will be zero and thereaction on wall will be inward in direction. When the base is sliding,there will be largest possible displacement but the reaction will be zero
Fro. 7 WALL WITH SHEAR ApPLIBD AT BAsa
. .3.1_6 J.~rQll wit" ~\lonu~' Applied at ,Top - When the top of the wall andf~, ltl~.,1"oofsial) are made continuo~s as shown in Fig. 8" the deflection of the
roof will tend to rotate the top j(xnt and introduce a moment at the-top ofthe ".a11. In such cases, data in Tables 16 and 17 will be found usefulalthough they are prepared fO.f moment applied at one end of tile wall when
12
D I 3370 ( Pan IV ). 1117
the other is free. These tables may also be applied with good degree ofaccuracy. when the free end is hinged or fixed.
FlO, 8 WALL WITH ~fO"BNT ApPLIED AT Tor-
3.1.7 Data for moments in cylindrical walls fixed at base and free at topalad subjected to rectangular load are covered in Table 18, and the datafor momene in cylindrical wall, fixed at base, free at top, subjected to shearapplied at the top arecovered in Table 19.
3.2 Mo...t. i. Clftular Slab. - Data for moments in circular slabswith varioul edge conditions and subjected to different loadings are givenin Tables 20 to 23.. .
IS
II. JS7I ( Part IV ) • 1967
TAo.U 1 MOMENT coanCIENTS FOR INDIVIDUAL WALL PANEL.TOP AND BOTTOM lUNGED. VERTICAL ItDOEI FIXED
(CltlftS's 2_1, 2.•2 .nd 2.2.2 )
t-td .& hrighi (If tl-e wall y
6 - width of the \"all
UI - density of the liquid
Hnnlontal moment 'C:' l\f" It,.3
\'c(tical moment .;::: ~V~ Uta'
X0/4 x]« -':LO J' -= 6/1t .1 CI 6/2
""--~ r . -4f "-----,
~Iz .1,1. M. M. Me Mfl(1) ,1..: (:i; (.f.) (5) (6) (7). (8)~-OO I,!'. +0·035 +0·010 +0·026 +0·011 -0·008 -0·039
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