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IS : 4935 ( Part I ) - 1974Indian Standard

CRITERIA FOR DESIGN OF REINFORCEDCONCRETE BINS FOR THE STORAGEOF GRANULAR AND POWDERY MATERIALS

PART I GENERAL REQUIREMENTS AND ASSESSMENTOF BIN LOADS

( First Rev ision )Third Reprint SEPTEMBER 1992

IJDC 62495301245

0 Copyright 1975BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SH AH ZAFAR MARG

NEW DELHI 110002

Gr 5 Augusr 1975

( Reaffirmed 1998 )

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IS : 4995( Part I I - 1974

Indian StandardCRITERIA FOR DESIGN OF REINFORCED

CONCRETE BINS FOR THE STORAGEOF GRANULAR AND POWDERY MATERIALSPART I GENERAL REQUIREMENTS AN D ASSESSMENTOF BIN LOADS

( First Revision )Criteria for Design of Structures Sectional Cornmittcr, BDC 38

ChairmanPnos G. S. RA~UIIYWANY

Members

R$rcscnfingSrru;~;rl~ginerring Rescilrch Centre ( CSIR ), L

SI~RIM. RAhrAIaH (Alternab toProf G. S. Ramaswamy )Dn B. M. AHUJA Indian Institute of Technology, New DelhiPROF*K. SEETH.%R.UIULU ( Alternate jSHEI B. K. CHaTTEn JEEDa Y. C. DAS nlis Chatterjee, Polk, Kukreja, New DelhiIndian Institute of Technology, KanpurDR P. DATARATN.~JI ( Alternate )

SHRI P. C. DAVEDEBP~;E;ECTOR ( STANDARDS ),b&TOR (TCD)Sun1 V. M. GADSHRI I

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( Cotiinucd from page 1 )Members Representing

SHRI B. K. JINDAL CentxaJorfe;ilding Research Institute ( CSIR ),SH~I B. S. GUPTA (Alternate)SHRI S. B. JOSEISHRI J. S. GOEIXALE ( Alternate)SH BI S. I. JOSH ISEBI K. C. KARAMCEANDANISEPI K. N. SINHA (Alternate )SHRI M. KUPPUSWA~Y

S. B.. Joshi & Co Ltd, BombayTata Consulting Engineers, BombayEngineers India Limited, New DelhiMinistry of Food & Agriculture (Department ofFood ), New DelhiSERI MAEENDBA RAJ In personal capacity ( Consulting Engineer, I.! ? E,Defence Colony, .New Delhi )Concrete Association of India, BombayEBI M. A. MEE TASHRI B. T. UN WALLA( Alternate )LT-COL M. H. S. MURTHY En gineer-in-Chiefs Bra nch, Army Headquarters

SO 2 ( DESIGNS ) ( Alternate)SEBI K. C. PANDYA M/s Shah & Pan dya, BombaySEEI B. BALWANT RAO Ministry of Transport (Roads Wing)SHRI S. SEE THA~AMAN ( Alternate )SEBI R. A. RAMA RAO The National Industrial Development CorporationLtd, New DelhiDR J . K. SRIDHAB RAO Nat iF: geyhyittee on Science and Technology,SHBI T. N. SUEBA RAO Gamzon India Ltd, BombaySERI P . B. PATI& ( Alternate)SHRI K. G. SALVI Hindu sta n Housing;Factory, New DelhiSHRI S. K. CHATTERJE E ( Alternate )DE B. R. SEN Indian Institute of Technology, Khar agpur

DR S. K. MALLICK ( Alternate )SHBI C. N . SRIN IVASAN M/s C. R. Na ra yana Rao, Madr asSUPERINTENDINQ SUFLVEYOR OF Centra l Public Works Depart ment , New DelhiWORKS ( I )SEBI V. VENKATESWABULU (Alternate)SEIU M. C. TANDON Stup India Ltd, BombaySHXI N. C. JAIN ( Alternate )SHRI R. N. VAKIL Vakil-Mehta-Sheth, C o n s u 1 t in g Engineers,AhmedabadPROF P. C. VAR~HESE lndian Inst itut e of Technology, Madra sDa S. SRI NIVASA RAO ( Alternate)SI~RI K. VEERAHAGBAVACHARY Bha ra t Hea vy Electricals Lt d, Tiruchirapa lliSHRI D. AJITHA SI~OIA, Director Gener al, I S1 ( Ex-officio Member)Director ( Civ Engg )

SecretarySHRI V. SURESHAssistant Director ( Civ Engg ), IS 1

( Continued on jagc 17 )

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IS : 4995 ( P a r t I ) - 1974

Indian StandardCRITERIA FOR DESIGN OF REINFORCED

CONCRETE BINS FOR THE STORAGEOF GRANULAR AND POWDERY MATERIALSPART I GENERAL REQUIREMENTS AND ASSESSMENTOF BIN LOADS

( First Revision )0. FOREWORD

0.1 This Indian Standard ( Part I ) ( First Revision ) was adopted by theIndian Standards Institution on 9 December 1974, after the draft finalizedby the Criteria for Design of Structures Sectional Committee had beenapproved by the Civil Engineering Division Council.0.2 Storage structures like bins (silos and bunkers ) for storing differentmaterials are one among the important structures coming up in anyindustrial or organized storage complex. The necessity to store and containmaterials like coke, coal, ores in the various steel plants and other industrialestablishments cannot be overemphasized. In cement factories as well asin construction projects, cement is stored in large silos, On the agriculturalfront the foodgrain storage structures play a vital role in ensuring the supplyof foodgrains at all times of the year. Bulk storage of materials in bins hascertain advantages over other forms of storage. Therefore, the necessity toformulate standard criteria Tar design of such structures has been felt andthis standard is aimed at giving the necessary guidelines to arrive at thestructural design of reinforced concrete bins for the storage of variousmaterials of different properties and characteristics.0.3 This standard published in 1968 covered the requirements of thestructural design for foodgrain storage bins ( silos ). It has been felt thatinstead of bringing out one separate standard to cover the requirements ofall materials other than foodgrains, it would he judicious to cover the subjectunder one standard in which provisions for bins storing diflerent matrrialscould be dealt with adequately. Therefore, the first revision of this standardhad been taken up to cover the requirements of storage bins for all materialsincluding foodgrains,

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IS : 4995 ( P a r t I ) - 19740.4 The different stored materials, such as coke, coal, ores, foodgrains,fertilizers, cement and flour can be classified either as granular or powderymaterials. Extensive research work all over the world has indicated thatassessment of bin loads caused due to a stored material would requiredifferent treatments depending upon whether it is a granular or powderymaterial. Considering this, the standard has now been brought out in twoparts, namely, Part I - General requirements and assessment of bin loads,and Part II - Design criteria.0.5 In the formulation of this standard due weightage has been given to thefindings of recent research and international coordination amongst thestandards and practices prevailing in different countries. This has beenmet with by referring to the following standards and publications:

DIN 1055 ( Sheet 6 ) Design loads for building-bin loads. November1964. Deutscher Normenausschuss.PIEPER (K) and WENZEL (F). Pressure distribution in bins 1964.Verlag von Wilhelm Ernst & Sohn, Berlin, Munchen.REISNER (W) and ROTHE (M E). Bins and bunkers for handling bulkmaterials. Trans. Tech. Publications, Ohio.

0.5.1 In view of the continuing research done on flow characteristics ofmaterials, the emphasis in the code is on structural adequacy of bins.However, as regards flow characteristics of the materials, the designerswould be well advised to consult the relevant litera,are. This code is basedon the latest available data and is amenable to review as and when morereliable information on this subject becomes available.0.6 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, shall be rounded off in accordance withIS : 2-1960*. The number of significant places retained in the rounded offvalue should be the same as that of the specified value in this standard

1. SCOPE1.1 This standard (Part I ) deals -with the general requirements andassessment of bin loads for granular and powdery materials.1.2 This standard covers circular, polygonal and interstice bins.1.3 This standard deals with the storage of materials in dry condition forwhich properties are given in Table 1. However, if moisture content,temperature, etc, vary, the actual values would have to be arrived at asindicated under Note of Table 1. Provisions for thermal insulations,

*Rules for rounding off numerical values ( revised).4

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IS : 4995 ( P a r t I ) - 1974details of joints, weather proofing of joints, etc, are not covered in thisstandard.2. TERMINOLOGY2.0 For the purpose of this standard, the following definitions shall apply.2.1 Aera t ion -A process in which air is moved through the storedmaterial for ventilation.2.2 Arching -A phenomenon in the bin during the emptying of a storedmaterial giving rise to formation of arches of the material across the binwalls.2.3 Bin - A storage structure, circular or polygonal in plan and intendedfor storing bulk materials in vertical direction. Silo is a bin circular orpolygonal in plan. Bunker is a bin whose cross section in plan would besquare or rectangular,2.4 B i n L o a d s - Loads exerted by a stored material on the walls of a bin.2.5 Foodgrain- All cereals, pulses, millets, except oil seeds.2.6 G r a n u l a r M a t e r i a l s - All materials having mean .particle size morethan 0.2 mm. No cohesion between the particles is assumed.2.7 In t e r s t i c e B in -B in that is formed out of the space enclosed by abattery of interconnected bins.2.8 Powdery Materials - All materials having mean particle size lessthan 006 mm.3. NOTATIONS3.1 For the purpose of this standard, the following notations shall have themeaning indicated against each:

A = Horizontal interior cross-sectional area of bin.a = Side of a square bin or shorter side of a rectangular bin,b = Longer side of a rectangular bin.D = Internal diameter of a circular bin.d = Maximum diameter of the circle that can be inscribed in thebin.h = Height of the bin.Pa - Pressure of air injected for pneumatic emptying of a bin.Ph = Horizontal pressure on bin walls due to stored material.Pi = Stands for Ph or P, or Pm as the case may be.

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IS : 4995 ( P a r t I ) - 1974Phi = Pressure obtained on the wall of a bin imagined to be enlargedin plan so as to make the eccentric opening concentric.P, = Vertical pressure on the horizontal cross section of the storedmaterial.P, = Vertical load transferred to the wall due to friction between

material stored and bin wall.R = A/U.11 = Interior perimeter of the bin.W 7 Bulk density of stored material.5 = Depth below the levelled surface of the maximum possible fillin the bin (Fig. 1 ).9 = Angle of internal friction of the stored material.6 = Angle of wall friction.h = Pressure ratio ( = PjL/Pw .A, = Pressure ratio during filling.he = Pressure ratio during emptying.!J = Coefficient of wall friction ( p= tan 6 ).Erf = CoefTicient of wall friction during filling.Ile = Coeficient of wall friction during emptying.

FIG. I DEPTH BELOW THE LEVELLED SURFACE OF THE MAXIMUMPOSSIBLEFILL IN THE BIN

4. GENERAL4.1 L o c a t i o n - Location of bins and specially those storing foodgrainsshall conform to the relevant provisions of IS : 3453-1966* and IS : 5503(Part I)-1969t.

*Code of practice for construction of hexagonal type of concrete-cum-masonry binsfor bulk storage of foodgrains.tGenera1 requirements for silos for grain storage: Part I Constructional requirements.6

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IS : 4995 ( P a r t I ) - 19744 .2 Ec o n o m ic C o n s id e r a t i o n s - Dimensions, shape and layout of thebins, etc shall be so arrived as to effect optimum economies, the details of\vhich are given in 4.2.1 to 4.2.3. In addition, the material handlingijcilities shall also be considered.

4.2.1 Dimensions - Volume of each bin and height to diameter ratio shallbe governed by its storage and functional requirements of materials. Toachieve a reduction in latera pressure over a larger height, it may bepreferable to select a height/diameter ratio greater than or equal to two.

4.2.2 Shabe- A bin may be circular or polygonal in plan and is providedwith a roof and bottom which may bc flat, conical and pyramidal. Incase of gravity flow bin, the angle made by the hopper with the horizontal,shall preferably be 15material. more than the angle of repose of the stored4.2.3 Layout - Storage bins may be either free standing individual binsor arranged in the form of batteries of free standing bins or bins inter-

connected in one or both the directions.5. DESIGN PARAMETERS5.0 Design parameters of stored materials include bulk density, angle ofinternal friction, angle of wall friction and pressure ratio ( X ) which arethe governing factors for the computation of bin loads. Storage and flowcharacteristics of granular materials differ \\-idely from those of powderymaterials.5.1 Sh ap e o f th e Bin - T i le cross-sectional shape of the bin is taken intoaccount by the factor R = A/ U. In the case of interstice bins, the value ofR shall be approximated by the value of R for an equivalent square bin ofthe same area.5.2 B u lk D e n s i t y a n d An g le o f I n t e r n a l F r i c t io n - Table 1 gives thevalues of bulk density and angle of internal friction for some of the com-monly stored materials.5.3 Wall F r ic t ion - In the absence of reliable experimental data, theangle of wall friction for granular and powdery materials: irrespective ofthe roughness of bin wall, may be taken as given in Table 2.

5.3.1 For materials having mean particle diameters in bctwecn 006 mmand 02 mm the necessary values of angle of wall friction may be obtainedby linear interpolation. If there is a possibility that the effect of moisture,pressure increase due to consolidation, etc, may chnngr the angle of wallfriction, 6 to a value than that indicated in Table 2, thrn its value shouldpreferably be determined experimentally.5.3.2 Pressure Raiio -For the purpose of computing bin loads, theratio of horizontal to vertical pressure, A, may 1)~ assumed as given inIable 2.

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IS : 4995 (Par t I ) - 1974TABLE 1 BULK DENSITY AND ANGLE OF INTE RNAL FRICTION OFSTORED MATERIALS

( Clnu ses 1.3, 5.2 n nd 6.2.1 )SL MATERIALNo.(1) (2)

i) Food gra ins an d m illed pr oducts:a) Wheatb) Paddyc) Riced) Maizee) Barleyf) Corng) Sugarh) Wheat flour

ii) Coal:

BULK DENSITY,( kgym3 )

(3)850575900800690800820700

iii)

iv)v)

a) Bituminous, dry an d brokenb) Raw ( 10 mm size)c) Pulverized, aera tedd) Pu lverized, compa ctedAnthracite:a) Dry an d brokenb) Pulverized, aer at edc) Pu lverized, compa ctedCoke:Dry, broken and looseAsh :a) Dry an d compa ctedb) Loosec) Fr om pulver ized fuel, dr y an d loose

vi) Ores:a) Ha emat ite ( 10 mm size)b) Magnetitec) Manganesed) Limestonee) Copper an d zincf) Lead

vii) Others:a) Cementb) Cemen t clinkerc) Pu lverized lime

8001 0405708908906509704307206501 120

3 70040002 570-2 9001 300-I 8002 570-Z 9005 250

1550 251 650 35-37I 350 25

ANGLE OB INTERNALFRICTION

283:;7273530

35225

ifi2530

it!3035353;3535

NOTE -The values given in Table 1 may not be ta ken to be applicableuniversally. The bulk density and angle of internal friction depend upon manyvariable factors, such a s moistur e conten t, par ticle size an d temper at ur e, etc.Wher ever possible t ests sha ll be condu cted on actua l samples to obta in th e abovevalues un der a ctual condit ions of stora ge.

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IS : 4995 ( Part I ) - 1974

SLNO

(1i)ii)

iii)

TABLE 2 ANGLE OF WALL F RICTION AND PRE SSURE RATIO( Clau ses 5.3, 5 3.1, 5.3.2 and 6.2.1 )

hIATI?RlAL

PjGranular materials with meanpar ticle diamet er 2 0.2 mmPowdery ma terials ( exceptwhea t flour ) with meanpar ticle diamet er

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IS : 4995 (P a r t I) - 1974along the bin height. However, where necessary, the variation of W and 5along the depth may be determined experimentally and used in the develop-ment-derivation-of Janssens theory for computation of bin loads. Designscan be carried out using mass/funnel flow characteristics, details for whichare not at present covered in the scope, and designers are well advised toconsult relevant literature.6.1 B i n L o a d s d u e t o Gr a n u l a r M a t e r i a l s

6.1.1 .Normal Filling and Empty ing6.1.1.1 Maximum pressures - The maximum values of the horizontalpressures on the wall (P,, ), the vertical pressure on the horizontal crosssection of the stored material ( P,, ) and the vertical load transferred to thewall per unit area due to friction ( P,,, ) shall be calculated as follows

( see also Fig. 2 ) :jVam e of Pressure During Filling During Emptying

Maximum P,,, W R W RMaximum Ph

Maximum P.

W Rt * f

W RPa

W RpJ,

6.1.1.2 PO and P, cannot be maximum at the same time. Hencefor the design of hopper bottom, maximum P, ( during filling ) should beconsidered and this value will be the maximum P, at the particular depthmultiplied by area of cross section of bin. The maximum P, ( emptying )shall be calculated when the side walls are to be designed at a particulardepth as:

7 \ - 4Pe /If h/D ratio is less than or equal to 2, the values shall be:

a) the total weight of stored material when hopper bottom is to bedesigned, andb) the value indicated as Pw when side walls are to be designed.

6.1.1.3 Variation of pressure along the depth -The variation of P,,pa and P, along the depth of the bin may be obtainedgiven below ( Fig. 3 ):

from the expression

pi ( 5 ) = ( Pi ) moz ( 1 -ezZ0 )10

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IS : 4995 (Part I ) - 1974where P stands for pressure and suffix i stands for w, h or v correspond-

ing to the pressures P,,,, Ph or P, respectively and zO assumes the valuesgiven below:

During filling, ,& = R/pfXfDuring emptying,

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IS : 4995 ( P a r t I) - 19746 .2 B in Lo ad s d u e t o P o w d e r y Ma t e r i a ls

6.2.1 Normal Filling and Empt ying - Maximum design pressures underthis case shall be computed as specified under 6.1. Appropriate valuesof various design parameters shall be taken from Tables 1 and 2.

6.2.2 Homogenization - In the case of homogenizing bin, the filling consistsof powdery materials which is circulated by compressed air for mixingpurposes. During homogenization of powdery materials the lateral andvertical pressures depend upon the volume of the empty space available inthe upper portion of the bin. This may be kept about 40 percent of thetotal volume of the bin. The lateral and vertical pressures shall becalculated using the following expression and should not be less thanpressure evaluated as in 6.1.1:Ph = P, = 0.6 W