8/14/2019 IS 9178 (Part 1) - 1978

1/39

IS : 9178 ( Part II ) - 1979( Reaffirmed 1995)

Indian StandardCRITERIA FOR DESIGN OF STEEL BINS FOR

STORAGE OF BULK MATERIALSPART II DESIGN CRITERIA

( Second Reprint OCTOBER 1997 )

UDC 624.953.041 : [669.14] : 621.796.6

0 Copyright 1980BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Gr 8 April 1980

8/14/2019 IS 9178 (Part 1) - 1978

2/39

IS:9179P8rt ll)-1979I ndi an St andard

CRITERIA FOR DESIGN OF STEEL BINS FORSTORAGE OF BULK MATERIALSPART II DESIGN CRITERIA

Structural Engineering Sectional Committee, SMBDC 7Chairman R+rwnting

DII~ECTO~STANDARDS CIVIL) Ministry of RailwayrM0llbHS

SEI~I R. M. AQARWAL Institution of Engineers ( India ), CLiIcuttaDx PREM KRISHNA ( Alternate )Snn~ A. K. BANERJEE Metallurgical and Engineering ConsultantsI India 1 Ltd. Ranchi\-- I ISHUI S. SANKARAN Altnnafe )SIIBI P. G. BA~~HAN Braithwaite 6 Co Ltd. CalcuttaSH~I S. K. GANQOPADHYAYAlternate )SHRI S. N. BASU Inspection Wing, Directorate General of Suppliand Dimorals. New DelhiSHRI D. B. JAIN ( Altcrnatc)San1 P. C. BHASIN Ministry of Shipping and Transport (Departmentof Transport ) ( Roads Wing )SZIRIV. S. BRIDE Central Water Commission, New DelhiDEPUTY DIRECTOR ( GATESAND DESIGNS ) ( Alfcrnalr )Dn P. N. CHATTERJEE Government of West BengalDR P. DAYARATNAX Indian Institute of Technology, KanpurSHEI D. S. DESAI M. N. Dastur Co Pvt Ltd, CalcuttaSHBI S. R. KULKA~NI ( Altwnatr )DIRECTOR TBAN~YIS~ION Central Electricity Authority, New DelhiDEPUTY DIBECTOR (Tsma-MISSION ) (Alternatu)JOINT DIREOTOR S T A N D A a D B Ministry of Railways

(B S)ASSISTANTDIBECTOR B S )-SB ( Altanatc )SERI K. K. KBANNA National Buildings Organization, New DelhiSHRI K. S. SRINIVAEAX Albnak ) (cmtimudon&a b2)@ Co right 1980.i.BUREAU OF INDIAN STANDARDS

This publication is protected under the Indian Cemkht Act ( XIV of 1957) andreproduction in whole or in port by any means except with written permission of thepublisher shall be deemed to be an infrintrement of convritvht under the raid Act.

8/14/2019 IS 9178 (Part 1) - 1978

3/39

IS : 9178 ( Part II) - 1979( Coatinued.fbm egs1)

Members RejmsentingSEZUP. K MALLICKSHRI S. MUKFIE~J EE J essop & Co Ltd, CalcuttaSteel Authority of India Ltd, New DelhiSasr S. K. MUKEE~J EE Bridge & Roof Co ( India ) Ltd, HowrahSRRI B. K. CRATTEBJ EI ( Alternate )SEUI P. N. BHASKARANNAIR

Snsx A. B. RIBEIRO ( Alternatr )SHRI R. NABAYANANPROP H. C. PARIUI~SWA~SHBI C. S. S. RAO ( Alternntc )SBRI DILIP PAULREPREEENTATIVESHRI A. P. KAYAL ( Alternate )RE~RE~ENTATXVE

Riil India Technical and Economics Services,New Delhi

REPRESENTATIVESHUI P. V. NAIK ( Alternate )

Structural Engineering Research Centre, MadrasEngineer-in-Chiefs Branch, Ministry of DefenceIndustrial Fasteners Association of India, CalcuttaBurn Standard Co Ltd, HowrahHindustan Steel Works Construction Ltd,CalcuttaRichardson & Cruddas Ltd, Bombay

S~nr P. S~NQUPTASHRI M. M. GHOSH Alternate )Snnr G. SRINIVASANStewarts & Lloyds of India Ltd, CalcuttaBharat Heavy Electricals Ltd, TiruchchirappalliS~nr G. L. NARASAIAH ( Alternate )SHRI D. SRINIVASANSnnr B. P. GIIOSIX Alternate ) J oint Plant Committee, CalcuttaSHBI M. D. T~AMBEKA~SHRI L. D. WADHWA Bomhay Port Trust, BombayEngineers India Ltd, New DelhiSHRI B. B. NAG ( Alternate )SHRI C. R. RAMA RILO,Director ( Strut & Met) Director General, BIS ( Ex-o#cio Member )

SHRI S. S. SETHIAssistant Director (Strut & Met ), BIS

Panel for Steel Silos and Bunkers, SMBDC 7/P-24

SERI K. VEEBABAQHAVAORAICYMembers

SHRI S. GOPALKBILIHNANBharat Heavy Electricals Ltd, Tiruchchirappalli

SHBI R. NABAY~AN ( Alfmutc ) Structural Engineering Research Centre, MadrasR~ESENTAIXVESH~I N. K. ROY Ministry of RailwaysFertiliier Fporation of Indi: Ltd, Sindri

2

8/14/2019 IS 9178 (Part 1) - 1978

4/39

8/14/2019 IS 9178 (Part 1) - 1978

5/39

IS : 9178 ( Part II ) - 1979requires frequent poking-manually, pneumatically with steam or by othermechanical means. With research data available, this problem has beensuccessfully solved by adopting mass flow or funnel flow bins where theshape of the bin hopper and size of the openings are based on the flowproperties of the stored material.0.6 In order to deal with the subject in an effective manner this standardhas been prepared in three parts namely:

Part I General requirements and assessment of loadsPart II Design criteriaPart III Bins designed for mass flow and funnel f l ow

0.7 This standard keeps in view the practices being followed in thecountry and elsewhere in this field. Assistance has also been derived fromthe following publications:

DIN 1055 ( Sheet 6 ) Design loads for building - Loads in silo/bins.Deutscher Normenausschuss.PIPEPER R ) and WENZEL F ). Pressure distribution in bins( in German ). 1964. Verlag Von Wilhelm Ernst & Sohn, Berlin,Munchen.REISNER ( W ) and ROTHE M E ). Bins%d bunkers for handlingbulk materials. Trans-Tech. Publication, Ohio, USA.LAMBERT ( F E ). The theory and practical design of bunkers.The British Constructional Steelwork Associations Ltd, London.JENIKE ( A W ). Storage and ilow of solids, Bull 123. 1964. UtahEngineering Experiment Station, University of Utah, Utah, USA.

0.8 For the purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculated, expres-sing the result of a test or analysis, shall be rounded off in accordancewith IS : 2-1960*. The number of significant places retained in thern*mded off value should be the same as that of the specified value in thisstandard.1.. SCOPE1.1 This standard ( Part II ) deals with the criteria for design of steel binsand analysis of forces for granular and powdery materials for different binshapes.1.2 This standard covers circular, polygonal and interstice bins.

*Rules for ounding off numerical values ( rcui sed ).4

8/14/2019 IS 9178 (Part 1) - 1978

6/39

1s : 9198 ( Part 11) - 19792. TERMINOLOGY2.1 For the purpose of this standard the definitions given in Part I inaddition to the following definitions shall apply.

2.1.1 Shal low Beam -A beam in which the depth ( height) to spanratio is less than 0.5. The stress distribution may be assumed linear.2.1.2 Deep Beam- A beam in which the depth ( height) to span ratiois greater than or equal to 0.5. The stress distribution is not linear.2.1.3 Corner Plate -A plate normally in the shape of a quadrant of acircle provided at the corners ( that is at the junction of the walls) of asteel bin for smooth flow of material.

3. NOTATION3.1 For the purpose of this standard the notations given in Part I shallapply in addition to the following:PI P P3 = Total horizontal loads due to pressure Ph

WI W _W = Total vertical loads due to pressure PM = Moment in the stiffenerT = Tension in the stiffener

H H = Bursting forceL B = Dimensions of the stiffenerII, Is = Moment of inertia of the stiffener

Z,, Ib = Moment of inertia of the shorter wall andlonger wall of the bins = Spacing between stiffenert = Thickness of wall plate

Tn = Tension due to circumferential stress on unitlength of the silo wallI, = Tension due to longitudinal stress per unitlength of circumference

r1 = Radius of hopper at the plane under considera-tionr2 = Mean radius of ring beam

hl h2 x x, y = Dimensions of bunker and hopper wall asshown in Fig. 1 and 2RN = Normal load acting on the sloping wall of

hopperRA RB , Rv = ReactionsP = Normal pressure

PtB Ptc = Tangential pressures5

8/14/2019 IS 9178 (Part 1) - 1978

7/39

IS : 9178 Part II ) - 1979Ii;

1 4

h

, t-434 - I3h2

1 C

J-1l(a)

Rc w3-?FIG. 1 FORCES INRECTANGULAR SYMMETRICALBUNKER

6

8/14/2019 IS 9178 (Part 1) - 1978

8/39

IS I 9178 ( Part II ) - 1979

H6 A F 4AW w4

hl I I

C Dx _YY_ X

1

FIQ. 2 FORCES N RECTANGULAR NSYMMETRICAL UNKER4. LOADS4.1 Dead and Live Loads - The dead and live loads on the bin struc-tures shall be as. given in IS : 875-1964*. The bulk density of variouscommonly stores materials are given in Table 2 of Part I .

4.1.1 Loads due to the stored material in the bin shall be assessedaccording to 6 of Part I of the standard.4.2 Wind Load - Unless otherwise specified wind load on bins shall becalculated in accordance with IS : 875-1964*.4.3 Seismic Forces -Unless otherwise specified seismic loads shall becalculated in accordance with IS : 1893-1975t.

NOTE - Wind and seismic forces shall not he assumed to act simultaneously.4.4 The effect of the super-imposed loads due to material handling andtransportation machinery shall also be considered in addition to the loadsspecified in 4.1 to 4.3.

*Code of practice for structural safety of buildings: Loading standards.tcriteria for earthquake resistant design of structures (third rcuiri~a ).

8/14/2019 IS 9178 (Part 1) - 1978

9/39

IS : 9178 ( Part Ii ) - 19795. MATERIAL5.1 Structural Steel - All structural steel used in the construction of binsshall conform to IS: 226-1975*, IS: 961-1975t and IS: 2062-1969$ asappropriate.5.2 Rivets - Rivets before fabrication shall comply with IS : 1148-19739or IS : 1149-197311.5.3 Bolts and Nuts --All bolts and nuts shall conform to IS : 1364-19677 and IS : 1367-1967**.5.4 Washers - Washers shall conform to IS : 20 16-1967tt.5.5 High Strength Friction Grip Fastener -- High strength frictiongrip fasteners shall conform to IS : 3757-1972$$.5.6 Electrodes Filler Material and Welding Consumables - Elect-rodes, filler material, flux, etc, used in welding shall conform to:

IS : 814 ( Part I )-1974 Specification for covered electrodes formetal arc welding of structural steel: Part I For weldingproducts other than sheets (fourt h revi si on )IS : 814 ( Part II )-I974 Specification for covered electrodes formetal arc welding of structural steel: Part II For welding sheets( fourth revision )IS : 1278-1972 Specification for filler rods and wires for gas weld-ing ( second rev i sion )IS; 36 13-1974 Acceptance tests for wire-flux combinations forsubmerged-arc welding of structural steels (jr st revi si on )IS : 6419-197 1 Filler rods and wires for inert gas welding of ferriticsteelsIS : 7280-1974 Base wire electrodes for submerged arc welding ofstructural steels

*Structural steel ( standard quality ) (f;fih revision ).Structural steel ( high tensile ) ( secondrevision ).*Structural steel ( fusion welding quality ) (first revision).Specification for hot rolled steel rivet bars ( up to 40 mm diameter ) for structuralpurposes ( second evision ) .IlSpeciiication for high tensile steel rivet bars for structural purposes ( second mision .l/Precision and semi-precision hexagon bolts, screws, nuts and lock nuts (diameterrange 6 to 39 mm ) (jrst revision ).**Technical supply conditions for threaded fasteners (Jrst revi sion ).ttSpecification for plain washers (first revision ).$ High-tensile friction grip bolts (Jirst revi sion ).

8/14/2019 IS 9178 (Part 1) - 1978

10/39

IS: 9178 ( Part ZI ) - 19395.7 Other materials used in association with steel work shall, where appro-priate Indian Standard exists, conform to such standards.6. PERMISSIBLE STRESSES6;1 Permissible stresses shall be as specified in IS : 800-1962*.7. GENERAL DESIGN REQUIREMENTS7.J ,General- The dimensions, shapes and layout of steel bins shallwnform to the relevant provisions of Part I of this standard.7.2 Qoors and Openings - Openings for filling, emptying, aeration, andfor instruments indicating the height of the stored material, quantity offlow, weight of stored material, etc, shall be provided. Manual accessshall be suitably provided.

7.2.1 Openings shall preferably be avoided in the zones of criticalstress.7.3 Supports - The arrangements for supporting the walls of a bin shalldepend upon the layout, the outlet openings, positions of the draw offconveyors, type of bin bottom, etc. The design of supporting structuresshall generally conform to the requirements of IS : 800-1962*.

7.3.1 If the bins form part of a building like power station, they shall besuitably connected to the beams and columns of such buildings.7.4 Foundations

7.4.1 The type of foundation for the storage bins shall be decided tak-ing into consideration the layout, site conditions, nature of soil and theload transferred.7.4.2 The bin structure shall rest on a reinforced concrete raft founda-tion, or pile foundations or isolated footings depending upon the soilconditions. Site investigation for foundation shall be carried out inaccordance with IS : 1892-1962t.7.4.3 In case,the reinforced concrete raft is to be laid over the piles thetop of the rnbt shall be at the plinth level.*Code of practice for use of structural steel in general building construction

( revised ) .t&de of practice for site investigations for foundations.9

8/14/2019 IS 9178 (Part 1) - 1978

11/39

I8: 9178 ( Part II ) - 19797.4.4 Design of foundation shall be carried out in accordance with theprovisions of IS : 456-1978*, IS : 1080-1962t, IS : 2911 (Part I)-1964sand IS : 2950 ( Part I)-1973s as appropriate.

8. GENERAL DESIGN CRITERIA8.1 For the design of steel bins the provisions contained in IS : 800-196211shall be applicable in conjunction with the provisions of this standard.9. ANALYSIS OF FORCES AND MOMENTS OF BINSSTRUCTURES9.0 General - The normally used method of analyzing single compart-ment bins is specified in this standard. The intensity of load at anyparticular depth is considered uniform.9.1 Bunkers with Horizontally Spanning Walls - If the bunker isrectangular and the moments of inertia of the side walls are different, thevalue of corner moment M at any horizontal cross section of bunker shallbe calculated as follows: - P 63 I, + a3 b--M = 12 1 b.1, + a Ib 1where P = calculated intensity of horizontal wall loads due to storedmaterial assumed to be uniformly acting on any horizontalcross section of bunker

a = breadth of binb = length of binIb = moment of inertia of longer wall& = moment of inertia of the shorter wall

If I, = Ib

If the bin is square, that is if II - b thenhi= - Pas____ = - 0083 Paz12

NOTE -The horizontal pressuresvary along the height of the bunker wall. Hencet h e bending moments and tensions also vary likewise.*Code of practice for plain and reinforced concrete ( U&d r e v i s i o n .*Code of practice for design and construction of simple spread foundations.fCode of practice for design and construction of pile foundations: Part I Load-bear-ing concrete piles.FjCode of practice for design and construction of raft foundations: Part I Design(first r&ion ) .[ICode of practice for use of structural steel in general building construction( rcoised) .

10

8/14/2019 IS 9178 (Part 1) - 1978

12/39

IS : 9178 ( Part II ) - 19799.2 Symmetrical Bunkers with Trough Bottom - In view of thesymmetry, only half the bunker is analyzed considering unit length of thebin [ see Fig. 1 (a) 1. Above the waist, the two forces causing bursting are:

The bursting force across the waist and at the discharge orifice levelare:H,,= + a C

hcvl - + w+ +w, x - P2 __- Pa- 1Ha = f hit+ w3x + f&2- 2fl2a +p37 1wherePI, Pz, and Pa are total horizontal forces as shown in Fig. l(a)due to pressure Ph ( see 6 of Part I of this standard ); andWI, W,, W3 are total vertical loads as shown in Fig. 1 (a) dueto pressure Pv ( see 6 of Part I of this standard ).

9.2.1 Slopi ng Si de of t he Hopper -- If Pnn and P,,c are the normalpressures at B and C the total normal load acting on the sloping wall is:RN = P,c: + PnB ._2 1x lant height

Pnc + PrlB___..- 2 1x z cosec ~9RN acts through the centre of gravity of the pressure diagram as

shown in Fig. l(b).The vertical and horizontal reactions at B and C may be resolvedto give the normal and tangential components required to design thetrough stiffeners [ see Fig. 1 (c) 1.R, = R. Cos f? - Hn Sin 0Rc = Ho Sin 6 - W3 COS 0TB = Rv Sin 0 + Hs COS 8TO = Hc Cos e + W, Sin B

and RN = RB + R.whereRr = WI+ Ws + W3

11

8/14/2019 IS 9178 (Part 1) - 1978

13/39

IS : 9178 ( Part II ) - 1979The final forcesand pressures required for the design calculationsare given in Fig. 1 (d).

9.3 Asymmetrical Bunker - The algebraic solutions given for symmetri-cal bunker may also be applied to bunkers which are not symmetricalabout a vertical line passing through the middle of the discharge opening.Such an arrangement with all vertical and horizontal forces is shown inFig. 2.Above the waist BE the horizontal forces have the same meaning asoutlined for the symmetrical case, that is:

Below the waist the following differences should be noted:HB HEHc Hn

R B RVEFor the steepest side:H,= CI-;-+W2+ -+W, x -I+&+- 1 ndzH c = -+ h, 2hz2 c WI++ W2+ + Wax + PST + Ps 3 1For the less steep side:

The vertical reactions are:R B = w, + w, + w3R E - w, + W6 + H,3It should be noted that the reactions Rv, and RvE are not thesimply supported beam reactions. This is because there is an out-of-balance

horizontal reaction at the outlet having the valueH = H D - H c12

8/14/2019 IS 9178 (Part 1) - 1978

14/39

IS t 9178 ( Port Ii ) - 1979Below the waist the horizontal forces should be in equilibrium, thatis:HB + Ps + Pa - Hc = 0,HE -+ P2 + P3 - HD = 0, and& - H,, = HE - HB.The procedure for calculating the normal and tangential pressuresand reactions is the same as for symmetrical bins.

9.4 Silos - The hoop tension T n. is calculated from the following formula ( see Fig. 3 ):T, = z+

9.4.1 Depending upon the manner in which the silo is supported theremay also be a longitudinal tension in the cylindrical portion.If the silo is supported at bbb ( see Fig. 3A ) the longitudinal tensionin the shell immediately below this plane will be due to the weight of thecontents plus the self weight of that part of the shell below bbb. If Wais the weight of the contents plus an allowance for self weight below bbb,then the longitudinal tension I;, per unit length of circumference shall be:

If the support is at AA, We will be the total combined weight ofthe contents and the weight of silo. However, if the silo is supported atthe waist BB which is preferable, then longitudinal tension shall beneglected for. the analysis of cylindrical portion of the silo.9.5 Hopper Bottom - The normal pressure P, and tangential pressurePt at any point on the hopper shall be calculated as follow:

P, = P, Cos2 0 + Ph Sin2 6 + W, Cos 0Pt = P ( 1 - A) Sin 8 Cos 8 + W, Sin 0or - (Pv- Ph ) Sin 0 Cos 8 + We Sin 6

whereW, - self weight of hopper per unit area.

9.5.1 Conical Hopper - Conical hoppers are generally subjected tomeridional and hoop tensions as the support is normally never below thewaist, ( see Fig. 3 ).13

8/14/2019 IS 9178 (Part 1) - 1978

15/39

IS : 9178 ( Part II ) - 1979

3A

38FIG. 3 PRESSURE

The hoop tension TE at any levelcalculated from the following formula:Trr = P yI Cosec 0

3cIN SILOSof the conical hopper shell be

The hoop tension will depend upon the vertical pressure acting onthe plate ccc plus the weight of material and the shell immediatelybelow the plane. If this total vertical load is Wt, then the longitudinaltension is:T - -EL Cosec 0L - 2xr1where

rr = radius at the plane under consideration.14

8/14/2019 IS 9178 (Part 1) - 1978

16/39

IS : 9178 Part II ) - 1979TL is maximum at the waist BB see Fig. 3 ) where IVt equals thetotal weight of the contents plus the self weight of the cone. Likewise the

minimum tension will occur at the outlet.9.5.2 Pyr ami dal H@fier - Pyramidal hoppers are subjected to bend-ing moments and direct tension in addition to meridional ( longitudinal)tension along the slope. The hoppers of polygonal bins shall be analyzedby considering each horizontal strip subjected to normal design pressureP, calculated as per 9.5. The meridional tension shall be calculated inthe same way as per conical hopper ( see 9.5.1 ).

9.5.3 Fl at Bottom or L evel Bottom - When no separate hopper isprovided, the flat bottom will be a flat plate or slab and will be subjectedto a maximum pressure equal to Pv.9.5.4 Secial Shapes - The hoppers may be of special shapes to suitparticular requirements like hopper for interstice bins and hoppers witheccentric discharge. In such cases the design should be based on soundengineering practice.

9.6 Multiple Compartments9.6.1 Multiple compartments are normally provided in rectangularbins. The bin should be designed taking into consideration the worstcombination of loads in different compartments.

10. STRUCTURAL DESIGN RECOMMENDATIONS FORBUNKERS10.1 General - The forces set up in a bunker induce direct, shear andbending stresses in its various parts. However, because of the shape it isnot economical to design the skin plate to resist all these stresses.

10.1.1 The rskin plate which form the bin wall is designed to spanbetween suitably positioned stiffeners which may be vertical or horizontaldepending upon the layout. Normally these stiffeners are arranged to actin the vertical plane.10.2 Skin Plate- The skin plate may be designed as a beam eithersimply supported or continuous between the stiffeners, which in turn alsoact as beams, but spanning at right angles to the designed direction ofskin plate.

10.2.1 The skin plates spanning between stiffeners are subjected tobending, shear and longitudinal stresses. Normally the plate is designedfor bending, the shear being neglected. The longitudinal tension is takenup on the stiffeners which may include a portion of the plate.15

8/14/2019 IS 9178 (Part 1) - 1978

17/39

IS: 9178 ( Part II ) - 197910.2.2 The plate generally spans in two directions simultaneously.Provided the ratio of length to width of the plate is less than 3 the advan-

tage may be taken of two-way bending.10.3 Side Walls - The side wall shall be designed as structure carryingboth vertical and horizontal loads. Based on the intensity of loads thestiffeners shall be provided either in the horizontal or in vertical planes.Hoppers are provided based on the need of a desired Bow pattern andcontrol on flow of stored material. Hoppers are also designed like a sidewall with stiffeners.10.3.1 The side walls may be designed as deep beams if the ratio of

depth to span is more than 0.5. The design loads shall include verticaland horizontal forces, and the longitudinal tension caused by the fillermaterial.10.3.2 A convenient method of designing the side wall is to proportionthe skin plate for side pressure only with stiffeners arranged either verti-cally or horizontally to suit the layout. The trough or cone reactions maythen be carried on a suitably designed beam situated immediately at thebottom of the wall.10.3.3 Vertical stiffeners when they extend for the full uninterrupteddepth of the wall, and are subjected to a triangular load distributionshall be designed to resist a bending moment of 0.0641 Pb.LJ, wherePb is the mean horizontal load on the uninterrupted depth of the stiffener.If they are interrupted due to the presence of horizontal stiffeners thebending moment for each separate length may be calculated as indicatedin 10.4.10.3A If the sticeners are arranged horizontally they will be subjected

to a uniformly distributed load, and may be designed either as simplysupported beams trimming into an extension of the corner supportcolumn, or where this is not possible as closed rings. In addition to thebending moment, horizontal stiffeners will also be subjected to directtension due to the pressure on the wall at right angles to the wall actuallybeing designed.10.3.5 Side wall stiffeners may be proportioned to include part of theskin plate ( see IS : 800-1962*),10.3.6 In Fig. 4 is shown a horizontalstiffener treated as a closed rec-tangular ring.*Code of practice for use of structural steel in general building constructiop

( reuised ) .16

8/14/2019 IS 9178 (Part 1) - 1978

18/39

1s I 9178 Part If. ) - 197910.3.6.1 The ring is in equilibrium ( see Fig. 4A ) under the load P,which is equal to the average pressure at the level being considered multi-plied by the distance between the stiffeners. As the ring is completely

symmetrical about the point 0, it is convenient to analyze one quadrantonly. In Fig. 4B this quadrant is shown under the influence of theload Ps; moments MA, M B and MC and tension TA and Tc, may be calcu-lated as follows:l- s B and= - 2

MA - z-g?C+3--2YzX+ 1 1M -p*LB (X+29)B=- (x+1)&fc = $s [Ya 3X+ 1) -2X]x+1)

Alternatively, the expressions for MA, MB, MC can be given asfollows:- P s 89

MB= 12 (x+ Y2)-T--+l)M* = PI 8 L2- + MB8

NOTE - Minus sign denotes tension on inside face of the ring.where

11 and Is = Moments of inertia of the ring as shown in Fig. 4B.The values of MA, M B and MC in terms of -$ and Y are given in

Table 1 by expressing the moments in the form M = n Ps L.17

8/14/2019 IS 9178 (Part 1) - 1978

19/39

- - +- __ 0

i4A 4B

FI G. 4 CLOSED RECTANGULAR RING STIFFENE RS

-ITABLE 1 COEFFICIENT A FOR CALCULATIN G THE MOMENT FOR CLOSED RECTANGULAR RINGS

( Clause 10.3.6.1 )S =1 r = 0 . 9 r = 0 . 8L I I

I z11 MA MB MC I MA MB MC MA Mk MC1-o0.9 0.041 6 0.083 34 0.04 166 0.049 16 0.075 84 0.025 42 0.053 99 0.070 01 0.010 06_ - - 0.049 58 0.075 42 0.025 83 0.055 78 0.069 22 0.010 78i 0.8 _ - 0.050 05 0,084 95 0.026 29 0.056 66 0.068 34 0.011660.7 _ - 0.050 56 0.074 44 0.026 28 0,057 66 0.012 678:; 1 - ) 0.051.051 846 0.073.073 846 0.027.028 429 0.058.060 802

:z;o0.064 88 0.013.015 813

II2 I 2 = 0.7 Y = 0.6 Y10.5--11 MA MB MC ( MA MB MC ( MA MB MC1.0 ' 0 . 059 6 0,065 84 - 0.004 59 0.06 1 65 0.063 35 - 0.018 34 0.062 50 0.062 50 - 0.031 250.9 0.060 26 0.064 74 - 0.003 48 0.062 99 0.062 01 - 0.017 00 0.063 98 0.061020.8 0,061 49 0,063 51 - 0.002 25 0.064 52 0.060 48 - 0.015 47 0.065 70 0.059 30 : :8:; ;:0.7 0 062 91 0 062 09 - 0,000 83 0066 27 0.058 33 - 0.013 72 0.067 69 0,057 31 - 0.026 04;:; 0.064.066 545 0,060058 465 0.000002 801 1 0.068 3250.070 0.056.054 685 - 0.011.009 674 0.072.070 061 0.054.052 094 - 0.023.020 837-

8/14/2019 IS 9178 (Part 1) - 1978

20/39

IS:9178 (Part II)-l ?10.4 Trough Stiffeners Trough stiffeners are those which give supportto hopper plate. These stiffeners are subjected to uniformly varyingpressures and direct tension ( see 9.2.1 nd Fig. 1 ). As the load is vary-ing, and assuming Pnc / P,u = y and a unit length of the bunker, thedistance y from the point B and the bending moment at this point aregiven as follow:

y = kL, andMY - (i P,B La

where L is the actual length of the trough stiffener. Values of kand 3 for different values of y are given in Table 2.

TABLE 2 VALUES OF COEFFICIENT J IAND k FOR DETERMININGTHE MAXIMUM MOMENT IN HOPPER STIFFENERSY k +

090 0.422 6 0.064 10.25 0.451 6 0,078 9o-50 0.472 6 o-094 00.75 0.490 4 0.109 41.00 0.500 0 0.125 01.25 0.509 2 0.140 61.50 0.516 6 0.156 4l-75 0.522 8 0.172 22.00 0.527 6 0.188 12.50 0.535 2 0.219 93.00 0.540 8 0.251 74.00 0.548 5 0.315 5

10.4.1 oupled with this bending moment, there will be the directtension having the value:T, = 7-B - [ PtB.y - ( PtB - P& yld

where Ptn and Ptc; are tangential pressures at B and C respectively,and I; = direct tension at a distance y from B.The moment M, and the direct tensionthe centre to centre distance of the stiffenersvalues required to proportion the stiffeners.

Z-, shall be multiplied byto give the actual design

19

8/14/2019 IS 9178 (Part 1) - 1978

21/39

IS t 9178 ( Part II ) 1979X0.4.2 Where T-type stiffeners are employed, the width of skin plateconsidered for composite action shall be as follows:

a) when s/t is less than 40, width = s, where s = spacing betweenstiffeners and t = thickness of skin plate.b) when s/t is equal to or more than 40, width shall not be morethan 40 t.

In any event the distance between centres of successive stiffenersshall not exceed 80 t.10.4.3 The skin plate in the hopper portion carries the entire load dueto PV and Pw. They shall be designed for this load in addition to themoment it will have to resist in spanning between stiffeners. The con-

nections between the plate and the top beams shall also be designed tocarry these additional loads.11. STRUCTURAL DESIGN RECOMMENDATIONS FOR SILOS11.1 The wall and the hopper of the silo shall be designea to resist theforces specified in 9.4 and 9.5.11.2 The stress so calculated in the wall plate shall be within the permis-sible limits specified in IS : 800-1962*. Stresses due to direct load andlongitudinal loads if any shall also be considered while determining thethickness of the wall plate.11.3 Stiffeners - In order to prevent local buckling ( wrinkling ) of theplates the silo shall be provided with circular and vertical stiffeners.

11.3.1 For silos with height not exceeding twice the nominal diameter,horizontal stiffeners shall be provided at a spacing not exceeding1 500 mm. Vertical stiffeners staggered in different panels shall beprovided at 3 000 mm spacing. The width of the stiffener plate shall be100 mm and the thickness shall be equal to the thickness of shell or 6 mmwhichever is more.11.3.2 Where the height exceeds twice the nominal diameter, stiffenersshall be provided as indicated in 11.3.1, but the spacing shall not exceed100 t or 1 000 mm whichever is less, t is the thickness of the plate.11.3.3 The thickness of the plate shall be decided taking into considera-tion the effect of stiffeners.*Code of practice for use of structural steel in general building constructionrcuised .

20

8/14/2019 IS 9178 (Part 1) - 1978

22/39

IS : 9178 ( Part II ) - 197912. MINIMUM THICKNESS OF PLATE12.1 The minimum thickness of plate excluding corrosion allowance shallbe 6 mm in the case of skin plate and 5 mm in the case of stiffcncrs.13. CORROSION ALLOWANCE13.1 Depending upon the exposure to atmosphere corrosion allowance onwall plate thickness shall be as follows:

4b)Cl4

Condit i on of Exposure Allowancemm

Completely exposed to atmosphereand no lining 5Completely exposed but lined insideNot exposed to atmosphere but notlined inside

41.5

Not exposed to atmosphere and linedinsideNo allowance

13.2 Corrosion allowance shall not be taken into consideration for stresscalculations.13.3 Where the atmosphere is polluted with corrosive substances specialallowance for corrosion shall be made depending on the degree of corro-sion expected.13.4 Where stored material induces wear and tear and/or affects theplates due to chemical reaction special precaution against corrosion shallbe taken by providing suitable lining,

14. CORNER PLATES14.1 In order to prevent stagnation of stored material at the corners andalso to facilitate easy flow corner plates shall be provided, and the mini-mum thickness shall be 6 mm.15. TEMPERATURE EFFECTS15.1 Stress due to temperature difference between the inside and outsideof the bins shall be calculated and accounted for in the design. Wheretemperature stress is substantial, for example, in multi-compartment binsand battery of bins, detailed investigation shall be carried out on theeffect of temperature variation.

21

8/14/2019 IS 9178 (Part 1) - 1978

23/39

IS I 9178 ( Part II ) - 197915.2 Temperature Stresses - Temperature stresses are introduced inthe bin structure mainly by filling the bin with the material which is eitherhot to start with or becomes hot later. The change in the atmospherictemperature may also lead to temperature stresses. Such stresses cangenerally be controlled to a satisfactory limit by suitably designing the binor by providing suitable insulation.16. FABRICATION16.1 For fabrication the provisions contained in IS : 800-1962*, IS : 816-1968r and IS : 323-1964s shall apply.16.2 In bins of welded construction the junction of walls inside the binshould be continuously welded to effect complete sealing, even if such con-tinuous welding is not required from strength point of view, This is toensure that moisture does not enter the stored material and that the storedmaterials do not leak out.16.3 In the case of members outside the bin structure, for examplestiffeners, intermittent welding may be adopted.17. CONSTRUCTION DETAILS17.1 Typical construction details of bins are given in Fig. 5 to 16 forinforrnaticn.17.2 A bunker with main vertical stiffeners is shown in Fig. 5. The useof main horizontal stiffeners is shown in Fig. 6.17.3 Typical details of hopper bottom are shown in Fig. 7.17*4 The typical details of the bunker where the side walls are designedas riecp beams are shown in Fig. 8. The details of hopper constructionarc also shown.17.5 The typical connection details of the hopper to the vertical wall withmain vertical stiffener are illustrated in Fig. 9. A box girder is employedas a horizontal stiffener at the junction of hopper and main wall. Similardetails but the vertical walls with horizontal main stiffener are shown inFig. 10.

*G)cle of practice for me of structllral steel in general building construction reoised).tCorie of practice lor use of metal arc welding for general construction in mild steelJir5t rraision ).ZCode of procedtrre for manual metal arc welding of mild steel.22

8/14/2019 IS 9178 (Part 1) - 1978

24/39

BOX STIFFENER t:;;,iim

FROJ T c =VhTiON SIDE ELEVATION i. I Lb_ I. 3ZV

FIG.~ TYPICALDETAIL OF STEEL BUNKER WCTHHOPPERBOTTON Ic1(WITH MAINVERTICAL STIFFEX~RS) scp

8/14/2019 IS 9178 (Part 1) - 1978

25/39

8/14/2019 IS 9178 (Part 1) - 1978

26/39

VERTICALSTIFFENERISME-CUT

k HORIZONTAL PLATESTIFFENERHORIZONTAL BUILT-UPTEE STIFFENER

FRONT CLEVATI~N SIDE ELEVATION

FIG. 7 TYPICAL DETAIL OF BOTTOM HOPPER OF STEEL BUNKER

8/14/2019 IS 9178 (Part 1) - 1978

27/39

I8 t 9178 ( Part II ) - 1979

TOP FLANGE[WALL OF BUNKER

Pj_ATE(OR) ISMB CUTSTIFFENERS TO RESISTHORIZONTAL FORCES

HORIZONTAL PLATE -----_- - _-_---STIFFENER--_

--------Y I-z ----_-_------_--

BOTTOM FLANGEBUNKER HOPPER PLATE --_-----------_

HORIZONTAL STIFFENER 2

FIG. 8 TYPICAL CONNECTION DETAILS OF SIDE WALLS,DESIGNED AS DEEP BEAM

26

8/14/2019 IS 9178 (Part 1) - 1978

28/39

8/14/2019 IS 9178 (Part 1) - 1978

29/39

8/14/2019 IS 9178 (Part 1) - 1978

30/39

IS : 9178 ( Part II ) - 1979

GlRDER SUPPORTINGTHE BUNKER

/CONNECTING BOLTS ONEITHER SIDE OF VERTI-CAL STIFFENERS

ATE STIFFENER

OARY HORIZONTALb15A;;J~fTICAL STIFFENER

FIG. 11 TYPICAL SUPPORTING ETAILS OF BUNKERWITH MAINSUPPORTING EAM(VERTICAL STIFFENERWITHOUTTRANSFERRING ORQUETO THE MAIN BEAM)

29

8/14/2019 IS 9178 (Part 1) - 1978

31/39

IS 2 9178 ( Part I ) - 1979

FIG. 12

-____---____---

MAIN HORIZONTALBOX STIFFENER

TYPICAL SUPPORTING DETAILS OF BUNKER WITHSUPPORTING BEAM

MAIN

WITM MAIN HORIZONTAL Box STIFFENERSAND SECONDARYVERTICAL STIFFENERS

30

8/14/2019 IS 9178 (Part 1) - 1978

32/39

wc

I- T-x D;$IIROF

HE

PLATE STIFFENERFLANGE PLATE

SECONDARY HORIZONTALPLATE STIFFENERMAIN VERTICAL STIFFENER

FIG. 13 TYPICAL SUPPORTING DETAILS OFBUNKER WITH MAIN SUPPORTING BEAMWITH MAIN VERTICAL ISMB CUT STIFFENERAND SECONDARYHORIZONTAL PLATE STIFFENERS

BUNKER SL PPORTINGGIF?@ER

VERTICAL PLATE STIFFENERFIG. 14 TYPICAL CONNECTION DETAILS OFWALL OF BUNKER WITH THESUPPORTINGGIRDER

8/14/2019 IS 9178 (Part 1) - 1978

33/39

8/14/2019 IS 9178 (Part 1) - 1978

34/39

IS : 9178( Part II ) - 1979

ITIFFENER

AIR PAD FOR

t VIEW-DD I-LD

DETAIL-bVIEW-AA

FIG. 16 TYPICAL DETAIL OF A ROCK PHOSPHATE SILO

33

8/14/2019 IS 9178 (Part 1) - 1978

35/39

8/14/2019 IS 9178 (Part 1) - 1978

36/39

iS t 9178 ( Part U ) - 1919APPENDIX ui

( lause 19.1 )SUPPORTING STRUCTURES FOR BINS

A-O. GENERALA-0.1 The method of supporting the bins depends on the location of thebins and the purpose to which it is intended,A-O.2 In case the bins are provided in the construction site for storingcement, sand and aggregate or for storing food grains or in the colleries,they should be supported by columns with provision for filling the bins andalso for removing the materials.A-O.3 The height of the bins opening at the bottom should be fixeddepending on the capacity and the method of discharging the storedmaterials.A-O.4 The materials may be conveyed through chutes by gravity oremptied into the lorries or small wagons. Accordingly, the bottom of thehopper shall be kept 3 to 5 m above ground level and properlysupported.A-l. DESIGNA-l.1 In addition to the forces exerted by the filled material, the forcesdue to wind or seismic force should be considered in proportioning thesupporting columns and beams.A-1.2 If the bins are circular, it shall be advantageous to support them atthe waist. This is normally done by providing a ring beam at this levelwhich in turn is supported on columns. The ring beam will be subjectedto axial force, bending, torsion and shear.

The ring compression P, the off setting lateral thrust of the fillingis not taken into account ) is calculated by the following formula:P, = w , cot f3

whereWd = total weight of bin with its contents and self weight ofthe ring beam, and

8 = slope of hopper walls.3s

8/14/2019 IS 9178 (Part 1) - 1978

37/39

18 : 9178 Part It ) - 1939 .A-1.3 The design shall be based on the maximum bending moment whichoccurs at the support. The torsional moment is zero at support andmaximum at the point of contraflexure.

The value of the bending moment at-support M and mid span Mmthe torsional moment n/r nd the location of the point of contraflexure Xon the ring of radius ~2 may be calculated from Table 3 ( gee Fig, 17 ).

FLEXURE

0 = the centre of the circle on which the supports lieA, B, c, D, E = supportsX = point of contraflexure

OL= angle at the wntre subtended by the two adjacent supports@ = angle at the point of contraflexure and the adjacent support make atthe centre

FIG. 17 RING BEAM SUPPORTING THE BUXKERA-I.4 The design of the column and beam shall be in accordance withIS : 800-1962*.

*Code of practice for use of structural steel in general building constructionrevised .

36

8/14/2019 IS 9178 (Part 1) - 1978

38/39

-TABLE 3 BENDI NG MOMENTS AND TORSIONAL MOMENTSIN SUPPORTING RING BEAMS

( Clause A-l .3 )No. OB

COLTJMNS

n

IO 3612 30

ANGULARSPACINGSTJPEL?:DE&~ )

120906045

LO D ATCOLUMNSrJPPOlZT

Waln

0334 wd 0.167 wd0.250 wd 0.125 w,0.167 wd 0.083 wd0.125 wd 0063 wdo loowd 0050 wd0.083 wd 0041 w,j

MAXSHEARWdb

MS MU P M t

I 1@062 93 Wdra i-0.033 29-0.034 15 wdrz 2548War2 +0.017 62 WdrZ 190-12-0.01482 Wdrz +0.007 51-0*008 27 +0*004 Wdrz 12~44Warpi 16 Wdrs 90-33-0 005 27 W,jrs +O-002 65 War2 7-37-0.00365 Wdr2 +O*OOl 90 War2 6-21 0.013 17 WdY.20.005 30 WdrsO*OOl51 W y*Of100 63 Wdra0900 32 War20300 185 Wdra

8/14/2019 IS 9178 (Part 1) - 1978

39/39

BUREAU OF INDIAN STANDARDSHaaiqmrtwsManak Bhavan. 9 Bahadur Shah Zafar Marg, NEW DELHI 110002Telephones: 323 0131, 323 3375, 323 9402Fax : 91 113234062, 91 113239399, 91 113239382 Telegrams : Manaksanstha

(Common to all Offices)Cm&a/ Laboratory TelephonePlot No. 20/9, Site IV, Sahibabad Industrial Area, SAHIBABAD 201010 8-77 00 32Regional Off icesCentral : Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002 323 76 17*Eastern : l/14 CIT Scheme VII M. V.I.P. Road, Maniktola, CALCUTTA700054 337 86 62Northern : SC0 335-336, Sector 34-A, CHANDlGARH 160022 60 38 43Southern : C.I.T. Campus, IV Cross Road, CHENNAI 600113 235 23 15twestern : Manakalaya. E9 Behind Mar01 Telephone Exchange, Andheri (East), 832 92 95

MUMBAl 400093Branch Of fhxs~Pushpak. Nurmohamed Shaikh Marg, Khanpur, AHMEDABAD 380001 550 13 48SPeenya Industrial Area, 1st Stage, Bangalore-Tumkur Road, 839 49 55

BANGALORE 560058Gangotri Complex, 5th Floor, Bhadbhada Road, T. T. Nagar, BHOPAL 462003 55 40 21Plot No. 62-63. Unit VI, Ganga Nagar, BHUBANESHWAR 751001 40 36 2;Kalaikathir Buildings, 670 Avinashi Road, COIMBATORE 641037 21 01 41Plot No. 43, Sector 16 A, Mathura Road, FARIDABAD 121001 8-28 88 01Savitri Complex, 116 G. T. Road, GHAZIABAD 201001 8-71 19 965315 Ward No. 29, R. G. Barua Road, 5th By-lane, GUWAHATl 781003 5411 375-8-58C. L. N.,Gupta Marg. Nampally Station Road, HYDERABAD 500001 20 10 83E-52, Chitaranjan Marg. C-Scheme, JAIPUR 302001 37 29 251171418 B. Sarvodaya Nagar. KANPUR 208005 21 6876Seth Bhawan. 2nd Floor, Behind Leela Cinema, Naval Kishore Road, 23 89 23

LUCKNOW 226001Patliputra Industrial Estate, PATNA 800013 26 23 05T. C. No. 14/1421. University P. 0. Palsyam. 6 21 17

THIRUVANANTHAPURAM 695034NIT Building, Second Floor. Gokulpat Market, NAGPUR 440010Institution of Engineers ( India ) Building, 1332 Shivaji Nagar, PUNE 411005

52 51 7132 36 35

Sales Office is at 5 Chowringhee Approach, P. 0. Princep Street,CALCUTTA 700072tSales Office is at Novelty Chambers, Grant Road, MUMBAI 400007

27 10 85309 65 28