IS : 4935 ( Part I ) - 1974Indian Standard ( Reaffirmed 1998 ) CRITERIA FOR DESIGN OF REINFORCED CONCRETE BINS FOR THE STORAGE OF GRANULAR AND POWDERY MATERIALS PART I GENERAL REQUIREMENTS OF BIN LOADS AND ASSESSMENT ( First Revision) Third Reprint SEPTEMBER 1992 IJDC 624’953’012’45 0 Copyright 1975 INDIAN STANDARDS SHAH 110002 ZAFAR MARG BUREAU MANAK OF BHAVAN, 9 BAHADUR DELHI NEW Gr 5 Augusr 1975 IS : 4995( Part I I- 1974 Indian Standard CRITERIA FOR DESIGN OF REINFORCED CONCRETE BINS FOR THE STORAGE OF GRANULAR AND POWDERY MATERIALS PART I GENERAL REQUIREMENTS AND ASSESSMENT OF BIN LOADS ( First Revision ) of Structures Sectional Cornmittcr, R$rcscnfing Srru;~;rl~ginerring Criteria for Design BDC 38 Chairman Pnos G. S. RA~UIIYWANY Members ’ L Rescilrch Centre ( CSIR ), Prof G. S. Ramaswamy ) Indian Institute of Technology, New Delhi Dn B. M. AHUJA PROF*K. SEETH.%R.UIULU ( Alternate j nlis Chatterjee, Polk, Kukreja, New Delhi SHEI B. K. CHaTTEn JEE Da Y. C. DAS Indian Institute of Technology, Kanpur DR P. DATARATN.~JI ( Alternate ) Drvclopment Consultants Pvt Ltd, Calcutta SHRI P. C. DAVE DEBP~;E;ECTOR ( STANDARDS ), Research Designs SC Standards Organization ( Ministry of Railways), Lucknow b&TOR (TCD) Central Water Sr Power Commission, New Delhi Sun1 V. M. GAD Atomic Energy Commission, Bombay SHRI I<. C. GHOSAL Alokudyog Cement Service, Sawai Madhopur SH~I X. D. GUPTA Fertilizer Corporation of India, Sindri Smt~ V. G. HEGDE National Buildings Organization, New Delhi SHRI A. C. GUPT.~ ( Altcnlate ) SRIZI G. S. IYER Hindustan Construction Co Ltd, Bombay SIIRI V. S. KA~IATH ( d&mate) Dn 0. P. JOIN University of Roorkee, Roorkee ( Continued on page 2 J @ Copyright 1975 STANDARDS SI~RI M. RAhrAIaH (Alternab to BUREAU OF INDIAN This publication is protected under the Zndiun Copyright Act ( XIV of 1957) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed 10 be an infringement of copyright under rhe said Act. GOEIXALE ( Alternate) SHBI S. AJITHA SI~OIA. B. Bombay SEIU M. SUEBA RAO SERI P. SEN Indian Institute of Technology. I’.( Cotiinucd from page 1 ) Representing CentxaJorfe. JOSHI SEBI K. C. R.!? E. Bombay SHBI T. RAMA RAO DR J. Madras PROF P. VENKATESWABULU (Alternate) Stup India Ltd. K.. MURTHY SO 2 ( DESIGNS ) ( Alternate) SEBI K. K. Bombay Ministry of Transport (Roads Wing) ) The National Industrial Development Corporation Ltd. C. Bombay Tata Consulting Engineers. N. G. SHRI R. N. IS1 ( Ex-officio Member) SHRI D. UNWALLA( Alternate ) LT-COL M. R. C. Defence Colony. Director ( Civ Engg ) Secretary SHRI V. New Delhi SHRI S. CHATTERJEE ( Alternate ) DE B. Army Headquarters M/s Shah & Pandya. SEETHA~AMAN ( Alternate SEBI R. B. S. MALLICK ( Alternate ) M/s C. JAIN ( Alternate ) C o n s u 1 t in g Engineers. JINDAL SH~I B. Vakil-Mehta-Sheth. KARAMCEANDANI SEPI K. A. Narayana Rao. B. Members SHRI B. T. S. C. N. Bombay Engineer-in-Chief’s Branch. MEETA SHRI B. SINHA ( Alternate ) SHRI M. New Delhi Ministry of Food & Agriculture (Department of Food ).New Delhi ) Concrete Association of India. SRINIVASA RAO ( Alternate) SI~RI K. New Delhi NatiF: geyhyittee on Science and Technology. JOSEI SHRI J. Tiruchirapalli Director General. New Delhi In personal capacity ( Consulting Engineer. . SRINIVASAN SUPERINTENDINQ SUFLVEYOR OF Central Public Works Department. VAR~HESE Da S. BALWANT RAO SHRI S. KUPPUSWA~Y SERI MAEENDBA RAJ SEBI M. SRIDHAB RAO S. VEERAHAGBAVACHARY Bharat Heavy Electricals Ltd. Bombay Engineers India Limited. S. SURESH Assistant Director ( Civ Engg ). Joshi & Co Ltd. GUPTA (Alternate) SHRI S. I. IS1 ( Continued on jagc 17 ) . PATI& ( Alternate) SHRI K. Gamzon India Ltd. VAKIL Ahmedabad lndian Institute of Technology.ilding Research Institute ( CSIR ). New Delhi WORKS ( I ) SEBI V. N. PANDYA SEEI B. C. TANDON SHXI N. A. K. Kharagpur DR S. K. SALVI Hindustan Housing.Factory. Madras SHBI C. H. coal. ores in the various steel plants and other industrial establishments cannot be overemphasized. On the agricultural front the foodgrain storage structures play a vital role in ensuring the supply of foodgrains at all times of the year. 0.2 Storage structures like bins (silos and bunkers ) for storing different materials are one among the important structures coming up in any industrial or organized storage complex. Bulk storage of materials in bins has certain advantages over other forms of storage. 0.IS : 4995 ( Part I ) . It has been felt that instead of bringing out one separate standard to cover the requirements of all materials other than foodgrains. 0. In cement factories as well as in construction projects. the first revision of this standard had been taken up to cover the requirements of storage bins for all materials including foodgrains. The necessity to store and contain materials like coke. 3 . Therefore. cement is stored in large silos. after the draft finalized by the Criteria for Design of Structures Sectional Committee had been approved by the Civil Engineering Division Council. Therefore.3 This standard published in 1968 covered the requirements of the structural design for foodgrain storage bins ( silos ). the necessity to formulate standard criteria Tar design of such structures has been felt and this standard is aimed at giving the necessary guidelines to arrive at the structural design of reinforced concrete bins for the storage of various materials of different properties and characteristics.1 This FOREWORD Indian Standard ( Part I ) ( First Revision ) was adopted by the Indian Standards Institution on 9 December 1974.1974 Indian Standard CRITERIA FOR DESIGN OF REINFORCED CONCRETE BINS FOR THE STORAGE OF GRANULAR AND POWDERY MATERIALS PART I GENERAL REQUIREMENTS OF BIN LOADS AND ASSESSMENT ( First Revision ) 0. it would he judicious to cover the subject under one standard in which provisions for bins storing diflerent matrrials could be dealt with adequately. 4 . the standard has now been brought out in two parts. the actual values would have to be arrived at as indicated under Note of Table 1. coal.5. etc.are.1974 0. Pressure distribution in bins von Wilhelm Ernst & Sohn. 0. Munchen.2 This standard covers circular. foodgrains.3 This standard deals with the storage of materials in dry condition for which properties are given in Table 1. Berlin. the designers This code is based would be well advised to consult the relevant litera. *Rules for rounding off numerical values ( revised). This has been met with by referring to the following standards and publications: DIN 1055 ( Sheet 6 ) Design loads for building-bin 1964. and Part II .IS : 4995 ( Part I ) . if moisture content. the final value. on the latest available data and is amenable to review as and when more reliable information on this subject becomes available. Tech. as regards flow characteristics of the materials. shall be rounded off in accordance The number of significant places retained in the rounded off IS : 2-1960*. Publications.Design criteria. Extensive research work all over the world has indicated that assessment of bin loads caused due to a stored material would require different treatments depending upon whether it is a granular or powdery material. 1. expressing with the result of a test or analysis. Provisions for thermal insulations. observed or calculated. Part I . 0. Deutscher Normenausschuss.4 The different stored materials. the emphasis in the code is on structural adequacy of bins. 0. namely. and 1. such as coke. November 1964. bulk PIEPER (K) and WENZEL (F).General requirements and assessment of bin loads. value should be the same as that of the specified value in this standard 1. Trans. cement and flour can be classified either as granular or powdery materials. ores. However. Considering this.6 For the purpose of deciding whether a particular requirement of this standard is complied with. temperature.5 In the formulation of this standard due weightage has been given to the findings of recent research and international coordination amongst the standards and practices prevailing in different countries. vary.1 In view of the continuing research done on flow characteristics of materials. However.1 This standard (Part I ) deals -with the general requirements assessment of bin loads for granular and powdery materials. Bins and bunkers for handling materials. REISNER (W) and ROTHE (M E). Ohio. fertilizers. Verlag loads. polygonal and interstice bins. SCOPE 1. 3. circular or polygonal in plan and intended for storing bulk materials in vertical direction. pulses. 2. Silo is a bin circular or Bunker is a bin whose cross section in plan would be polygonal in plan. or Pm as the case may be. Ph in the Pa Pi Pressure of air injected Ph = Horizontal = Stands for or P. = Maximum diameter of the circle that can be inscribed bin. area of bin.A storage structure. square or rectangular.1974 details of joints. = Side of a square bin or shorter side of a rectangular side of a rectangular D d h = Internal diameter of a circular bin.IS : 4995 ( Part I ) . weather proofing of joints. 2. millets.0 For the purpose of this standard.3 Bin .5 Foodgrain2.particle No cohesion between the particles is assumed. except oil seeds.All materials having mean . are not covered in this 2.4 Bin Loads Loads exerted by a stored material on the walls of a bin. the stored which is moved 2. = Height of the bin. 2. in the following air definitions through shall apply. meaning indicated against each: the following notations shall have the A a b = Horizontal = Longer interior cross-sectional bin. 2. standard. NOTATIONS All enclosed particle size less 3.2 mm. pressure on bin walls due to stored material.7 Interstice Bin -Bin that battery of interconnected bins.1 Aeration -A process material for ventilation. 2. etc.2 Arching -A phenomenon in the bin during the emptying of a stored material giving rise to formation of arches of the material across the bin walls.6 Granular than 0. TERMINOLOGY 2. is formed materials out of the space having mean size more by a 2. Materials .1 For the purpose of this standard. 5 . bin. for pneumatic emptying of a bin.8 Powdery Materials than 0’06 mm. All cereals. ( p= tan 6 ). pressure on the horizontal cross section of the stored between load transferred stored and to the wall due to friction bin wall. 1 ). = Pressure ratio ( = PjL/Pw ). surface of the maximum possible fill W 7 Bulk density of stored material. during emptying. emptying. filling. 11 = Interior 5 9 6 h he !J perimeter of the bin.IS : 4995 ( Part I ) .1974 Phi = Pressure obtained P. during filling.Location of shall conform to the relevant (Part I)-1969t. = Angle of internal friction of the stored material. = Vertical material on the wall of a bin imagined to be enlarged in plan so as to make the eccentric opening concentric. = Angle of wall friction. tGenera1 requirements for silos for grain storage: Part I Constructional requirements. I DEPTH BELOW THE LEVELLED SURFACE OF THE MAXIMUM POSSIBLE FILL IN THE BIN 4. = Depth below the levelled in the bin (Fig. R = A/U. = Pressure ratio during of wall friction Erf = CoefTicient of wall friction of wall friction Ile = Coeficient FIG. GENERAL 4. = Pressure = Coefficient ratio during A. bins and specially those storing foodgrains provisions of IS : 3453-1966* and IS : 5503 *Code of practice for construction of hexagonal type of concrete-cum-masonry bins for bulk storage of foodgrains.1 Location . = Vertical P. 6 . material. 5. angle of internal friction. In the case of interstice bins.2. To achieve a reduction in latera pressure over a larger height.2 ShabeA bin may be circular or polygonal in plan and is provided with a roof and bottom which may bc flat.Table 1 gives the values of bulk density and angle of internal friction for some of the commonly stored materials.Dimensions.2. etc shall be so arrived as to effect optimum economies.2 Economic Considerations . 5.2.IS : 4995 ( Part I ) .0 Design parameters of stored materials include bulk density. shape and layout of the bins.3. 4. 7 .1 For materials having mean particle diameters in bctwecn 0’06 mm and 02 mm the necessary values of angle of wall friction may be obtained If there is a possibility that the effect of moisture. thrn its value should preferably be determined experimentally.3 Wall Friction .Storage bins may be either free standing individual bins or arranged in the form of batteries of free standing bins or bins interconnected in one or both the directions. In case of gravity flow bin. may be taken as given in Table ‘2. may 1)~ assumed as given in ‘I‘able 2. DESIGN PARAMETERS 5.1974 4. 5. the material handling ijcilities shall also be considered. 5.2 Pressure Raiio -For the purpose of computing bin loads. characteristics of granular materials differ \\-idely from those of powdery materials. In addition.2. A.3 Layout .1 to 4. the angle made by the hopper with the horizontal. etc. 5.2. the angle of wall friction for granular and powdery materials: irrespective of the roughness of bin wall. by linear interpolation. 4. it may be preferable to select a height/diameter ratio greater than or equal to two.1 Shape of the Bin .In the absence of reliable experimental data.3. shall preferably be 15” more than the angle of repose of the stored material. may chnngr the angle of wall pressure increase due to consolidation. conical and pyramidal. angle of wall friction and pressure ratio ( X ) which are Storage and flow the governing factors for the computation of bin loads. the details of \vhich are given in 4. 5. the ratio of horizontal to vertical pressure.Volume of each bin and height to diameter ratio shall be governed by its storage and functional requirements of materials.3.Tile cross-sectional shape of the bin is taken into account by the factor R = A/U.1 Dimensions . friction. the value of R shall be approximated by the value of R for an equivalent square bin of the same area. 4. 6 to a value than that indicated in Table 2.2 Bulk Density and Angle of Internal Friction . compacted Wheat Paddy Rice Maize Barley Corn Sugar Wheat flour 28 3”: . MATERIAL BULK DENSITY. broken and loose v) Ash a) b) c) vi) Ores: a) b) c) d) e) f) a) b) c) Haematite ( 10 mm size) Magnetite Manganese Limestone Copper and zinc Lead Cement Cement clinker Pulverized lime 35 35 3”. The bulk density and angle of internal friction depend upon many variable factors.2. Wherever possible tests shall be conducted on actual samples to obtain the above values under actual conditions of storage.IS : 4995 (Part TABLE 1 I ) . etc. particle size and temperature.1974 DENSITY AND ANGLE OF INTERNAL STORED MATERIALS ( Clnuses 1. compacted Dry and broken Pulverized. 5.3. aerated Pulverized. . ( kgym3 ) (3) 850 575 900 800 690 800 820 700 800 1 040 570 890 890 650 970 430 720 650 1 120 3 700 4000 2 570-2 900 1 300-I 800 2 570-Z 900 5 250 1550 1 650 I 350 ANGLE OB INTERNAL FRICTION (2) (1) i) Food grains and milled products: a) b) c) d) e) f) g) h) ii) Coal: a) b) c) d) a) b) c) Bituminous. dry and broken Raw ( 10 mm size) Pulverized. aerated Pulverized.“7 27 35 30 35 2 25 iii) Anthracite: ifi 25 30 iv) Coke: Dry.2 nnd 6.1 ) FRICTION OF BULK SL No. dry and loose it! 30 vii) Others: NOTE-The values given in Table 1 may not be taken to be applicable universally. 35 35 25 35-37 25 : Dry and compacted Loose From pulverized fuel. such as moisture content. 1.5 0.0. 2 BIN LOADS 6.3. ASSESSMENT OF BIN LOADS 6.. load or horizontal pressure ( PA ) acting on the side b) vertical load or vertical pressure area of the bin filling.2 mm Powdery materials ( except mean wheat flour ) with particle diameter <0.7 (‘1 i) ii) Pj Granular materials with mean particle diameter 2 0. are assumed to be constant 9 . 5 3. P.There are three types of loads caused by a stored material in a bin as shown in Fig. A r___-h_--~ While \Vhile Filling Emptying (5) 0.3.1 ) SL NO hIATI?RlAL ASQLE oF1VAI.6 4 1.0 Bin Loads . They are: a) horizontal walls.06 mm Wheat flour iii) 0.IS : 4995 ( Part I ) .2. 6 r----~__-~ \Vhile \Vhile Filling Emptying (3) 0.L FRICTION. this standard Janssen’s theory has been used for the assessment In of bin loads in which the value of A. and ( P. ) introduced pw La FIG.1974 TABLE 2 ANGLE OF WALL FRICTION AND PRESSURE RATIO ( Clauses 5.0 # PRESSURE RATIO. 2.2 and 6.75 4 0. ) acting on the cross-sectional ( wall pressure c) frictional wall load or frictional into the side walls through wall friction. 5.7 6.5 (6) 1.75 $ 0.0 0.75 q$ 1.0 4 (4) 0.5 0. 6 and II. 1.Normal Filling and Emptying 6..1974 along the bin height.1.1 Maximum pressures . 3 ): pi ( 5 ) = ( Pi ) moz ( 1 -e’z’Z0 ) 10 .1 .1. the vertical pressure on the horizontal cross section of the stored material ( P. 6. details for which are not at present covered in the scope. can be carried out using mass/funnel flow characteristics.. 6. 2 ) : jVame of Pressure Maximum Maximum Maximum P.1. 7 \ - 4Pe / If h/D ratio is less than or equal to 2. pa and P. and b) the value indicated when hopper bottom is to be as Pw when side walls are to be designed.1.IS : 4995 (Part I) . the variation of W and 5 along the depth may be determined experimentally and used in the developDesigns ment-derivation-of Janssen’s theory for computation of bin loads.. ( emptying ) multiplied by area of cross section of bin. Ph P.2 PO and P. cannot be maximum at the same time. ). where necessary. the values’ shall be: a) the total weight of stored material designed. ) shall be calculated as follows ( see also Fig.. along the depth of the bin may be obtained from the expression given below ( Fig. shall be calculated when the side walls are to be designed at a particular depth as: 6.1. ) and the vertical load transferred to the wall per unit area due to friction ( P. During Filling WR WR t*f During Emptying WR WR Pa WR pJ.1.. at the particular depth The maximum P.3 Variation of pressure along the depth -The variation of P.1 Bin Loads due to Granular Materials 6.The maximum values of the horizontal pressures on the wall (P. Hence for the design of hopper bottom. However. maximum P. ( during filling ) should be considered and this value will be the maximum P.. and designers are well advised to consult relevant literature.. linear Appendix A gives the values Intermediate values may be interpolation. 3 indicated in Table PRESSURE VARIATION In 3 will give the governing 3 GOVERNING GRANULAR ALONG BIN DEPTH 6.IS : 4995 (Part where P stands ing to the pressures given below: for pressure P. = RIpehe of ( I-e-Z’Zo ) for different values obtained with sufhcient accuracy of by During filling. Ph or I) .4 Gooerning loading cases TABLE PRESSWRE ('1 P. I h FILLING PRESSURE Pi z OR 0*75h WHICHEVER IS LESS L REDUCTION DUE TO BIN BOTTOM k-d--d FIG. CASES POWDERY cases as LOADING MATERIAL hfATERIlL (3) (2) PIJ Emptying Emptying Filling 11 Filling = Emptying Filling = Emptying Filling .1.& = R/pfXf <‘. </&. the loading design pressures.1974 P. and suffix i stands for w. h or v correspondrespectively and zO assumes the values ...O ph general.. During emptying..1. This may be kept about 40 percent of the total volume of the bin.material being filled at a rate higher than the minimum filling speed . the pressures materials.6 W< 6.4 Pneumatic Embtying .6 I. actual filling speed.2.1 Application of the formula given in 6.3 Rapid Filling .2 Bin Loads due to Powdery Materials 6. = 0.During pneumatic emptying air under pressure is blown inside the bin through a number of small holes located in the bin walls near the bin bottom. a check should be made for the maximum pressure due to rapid filling from the greater values arrived at according to the formula given in 6.1974 6. The lateral and vertical pressures shall be calculated using the following expression and should not be less than pressure evaluated as in 6. in 6.2.2.3.shall be taken as follows: Material Cement Pulverized lime Wheat flour 00 2. 6.1 shall apply.2. Appropriate values of various design parameters shall be taken from Tables 1 and 2.1 Normal Filling and Emptying .2.1: Ph = P. 6. the upper stored material flows like a fluid. 6. v0 = the minimum filling speed. The values of ZJ.2.3 and the values given in 6. 6.Maximum design pressures under this case shall be computed as specified under 6. and t NOTE’- = time lapse of one hour.IS : 4995 ( Part I) .up to a certain height .& from the top layer.2.2. the filling consists of powdery materials which is circulated by compressed air for mixing purposes.2.4 and 6. m/h. However. This causes liquefaction of the material in 12 . The following expression may be used for computing the governing lateral pressures during rapid filling of a silo with a filling speed u: Rapid where & V filling (Ph) = 0’8 W& = = ( U-Uo) t. During homogenization of powdery materials the lateral and vertical pressures depend upon the volume of the empty space available in the upper portion of the bin.In the case of homogenizing bin.1.2 Homogenization .1.4 4.3.2.1.8 6. when the filling speed exceeds the minimum filling speed.3 is only for materials filled at a rate more than the minimum filling speed for different For speeds lesser than the minimum filling speed.2. m/h.During rapid filling . 1. This increased pressure shall be considered. where they have to be provided to meet functional requirements. Eccentric outlets in bins shall be avoided as far as possible.3. (both being equal ). Till more information is available. Pt.1.IS:49!95(Pa@tI)-1974 the lower portion of the bin and gives rise to higher values of Ph and P.1.3 Effects Causing 6. and Ph = horizontal pressure on the wall due to stored material. the increased pressure may be calculated as given under 6. 6. and. 4. The lateral pressures during pneumatic emptying shall be calculated as shown in Fig.1.3. due consideration shall be given in design to the increased pressure experienced by the walls.1 The additional pressure P’h shall be considered to act for the fuil height of the bin and is obtained from the expression given below: P’h = Phi where phi = pressure obtained on the wall of the bin imagined to be enlarged in plan so as to make the eccentric opening concentric.4 PRESSURE SCHEME FOR PNEUMATIC EMPTYING Increase in Bin Loads 6. 13 .1. to be acting both on the wall nearer to the outlet as well as on the wall on the opposite side.1 Eccentric Emptying-Eccentric emptying of a bin gives rise to increased horizontal loads non-uniformly distributed over the periphery and extending over the full height of the bin. (NORMAL FILLING) FIG.3. for the purpose of design. Ph Phi and Ph shall be obtained as per 6. p’ha ttttttttttt - -ENLARGED BIN J p’ha 5A RECTANGULAR BIN Qc I ECCENTRIC OUTLET ENLARGED BIN 5B CIRCULAR BIN FIG.3.1974 6. 5. 5 EFFECT OF EMPTYING THROUGH ECCIINTRIC OUTLETS 14 .IS k 4995 ( Part I ) .L2 The enlarged shape of the bin which is required for the purpose of computation of the pressure Phi shall be obtained as shown in Fig. 4 Effects Causing Decrease in Bin Loads .When bins are provided with equipment for ventilating the bin filling at rest. The vertical pressure on the bottom of the bin storing such materials shall be taken as twice the filling pressure..1.3.2 For powdery materials the measurements made so far do not indicate any significant increases in load when ventilating. 6. 6.IS : 4995 ( Part I ) . 6.3. From the level of the highest inlet upwards.3.3 Bins for storage of powdery materials are often equipped with devices (or pncumntic emptying. In all such cases the effective cross section of the bin is locally reduced. as calculated as per 6.3.1.3 Aeration of Stored Material .1. h owever the load need not be assumed to be greater. 6.Modern bins storing various materials may be provided with various discharge promoting devices such as inserts. 6. 6.Some stored materials arc susceptible to arching action across the bin walls. Therefore. than W. this increase in pressure may be tapered off uniformly down to zero at the top of the bin.3. 15 . no significant increases in load due to the air supply have so far been detected.In view of the load reducing effect of the bin bottom. emptying pressure at this height to the filling pressure at the bin bottom ( see also Fig. the horizontal pressure Ph. In this case also.3 The effect of eccentric outlets may be ignored in des?gn if the eccentricity is less than d/6 or the height of the bin is not greater than 2d. where d is the maximum possible diameter of the circle that can be inscribed in the bin. nrc to be increased by the inlet pressure of the air over that portion or the height of the bin in which the air inlets are located. a distinction must be made between bins for granular material and bins for powdery material.4 Discharge Promoting Devices G. In the absence of reliable knowledge available on the subject the designer is cautioned to assess the wall loads for such bins most judiciously and by carrying out experimental investigation. Recent research has given an intlicntion that in such bins the horizontal wall pressures arc esccssively incrcascd locally or along the tmtire bin height.1.3. an increase in the horizontal pressures is to be cxpectcd.3. P.3. bridge like structure above the outlet or relief nose.1974 6. 6.3. . The frequent collapse of such arches gives rise to increased vertical pressures.3. for fillin g. and thrsc bring about a loosening of the bin filling in the region of the outlet.2 Archiq of Stored Material .1 When the material is granular. the horizontal pressure during emptying may be reduced up to a height 1’2 d or 0’75 h whichever is smaller from This may be considered as varying linearly from the the bin bottom. 3 ).<. 945 0’950 (1) 3’1 3’2 3’3 33:.1. 0’7 0’8 0’9 1’0 1’1 1’2 .DDIX A ( Clause 6.I.981 6 8 7 3 6 8 7 (2) I.-z/z0 (1) 0’093 0’181 0’259 0’329 0’393 0’451 0’503 0’550 0’593 0’632 0’667 0’698 0’727 0’753 0.:.1.975 0’977 0.963 1 0’969 0’966 0.0 a 0’955 0 0’959 2 0.979 0.972 0.18:4995(PartI)-1974 APPEN. 1 5150 0’1 0’2 0’3 0’4 .776 (2) 2 3 2 7 5 2 4 7 4 1 1 8 5 4 9 (2) 0'798 0’817 0’834 0’850 0’864 0’877 0’689 0’899 0’909 0’917 0’925 0’932 0’939 0. 3’6 3’7 3.8 3’9 4.3 ) VALUES OF 1 -e-ZIzo FOR DIFFERENT VALUFS Z/Z.000 0 16 . 1’5 1 _ t-z/zo 1 -e-z /zo 1 3 7 4 7 5 2 7 3 9 7 8 2 0 2 -a& -. C. K. DAVE Development Consultants Pvt Ltd. RAMAXRI~HNA ( Alternate ) Gammon India Ltd. K. NAHAROY SHRI A.from pdgc 2 ) Panel tbr Reinforced Concrete Bins and Silos. Bombay SURI P. BATiL SHBI G. HARIDAEI f Alternate ) 17 . GOPALAKBISHNAN Roorkee Ministry of Food 8t Agriculture ( Department of SHRI M. VEERARAOHAVACHABY Bharat Heavy Repcwnting Electricals Ltd. Tiruchirapalli Members SEW P. KUPPTJSWAMY Food ). B.-R. Calcutta SHRI A. BDC 38 : P2 Convener SHRI K. MALLIK Engineering Construction Corporation Ltd.16:4995(P8rtI)-1974 ( Continucd. New Delhi Indian Institute of Technology. Kharagpur DE S. Madrar SHRI S. SHXI S. BHATTACHA~YYA ( Alternate ) Structural Engineering Research Centre ( CSIR ). University P. N. P. 5th Byelane. 9 Bahadur Shrh Zefar M8rg. G. V. Bombay 400007 SSales Office In Bangaloro Is at Unlty Building. 3 31 77 GUWAHATI 781003 S-8-56C L. Khanpur. Gupta Marg ( Nampally Station Road). 21843 1 31641 CHANDIGARH 160036 41 24 42 Southern : C. JAI PUR 302005 I 69832 21 68 76 117/418 B S8rVOd8y8 N8g8r. Naraslmharaja Square Bangalore 560002 Printed at Slmco Prlntina Pr*r*. BHUBANESHWAR 751002 5 36 27 5315.O. Road. P&yam 621 04 1621 17 TRIVANDRUM 695035 inspection Oft7ce (With Sale Point) : Pushpanjali. Nagar. No. NAGPUR 440010 Institution of Engineers ( India ) Building. 66716 BHOPAL 462003 Plot No. CALCUTTA 700054 Northern : SC0 445-446.I. 2 61 71 Shankar Nagar Square. Grant Road. 82/83. 27 6s 00 89 65 28 22 36 71 CMhi. 205-A West High Court Road. 5th Floor. Sector 35-C. I. Andheri (East). 331 01 31 [ 3311375 NEW DELHI-110002 ‘Eastern : 1 /14 C. E9 MIDC. IndIe . I. Campus.O. Prlncep Street. NEW DELHI 110002 Telegrams : Maneksanstha Talephones : 331 01 31. T. Ward No. PATNA 800013 62305 T.C. Marol. T. Bhadbhada Road. R. 1st Floor. 29. 1332 Shivaji Nagar. Bangalore Tumkur Road 38 49 55 BANGALORE 560058 138 49 56 Gangotri Complex. Lewis Road.. MADRAS 600113 412519 . P. KANPUR 208005 [ 21 82 92 Patliputra Industrial Estate. 9 Bahedur Shah Zafar Marg. 6329296 BOMBAY 400093 Branch Oflees: ‘Pushpak’ Nurmohamed Shaikh Marg. T. 1 st Stage. 23 1083 HYDERABAD 500001 63471 RI 4 Yudhister Marg. 1 41 2916 tWestern : Manakalaye. Scheme VII M. 331 13 75 ( Common to all offices ) Regional Oft7ces: Telephones Central : Manak Bhsvan. Calcutta 700072 tSales Ofice In Bombay Is at Novelty Chambers. 14/1421. 36 24 99 Maniktola. B8rU8 Road.BUREAU OF INDIAN STANDARDS Headquarters: Mansk Bhavan. 26348 AH M EDABAD 380001 [ 2 63 49 SPeenya Industrial Area. 52435 PUNE 411005 *Sales Office in Calcutta Is at 5 Chowringhee Approach. C Scheme.T. 2 d OR Cb75h AIR INLET HOSES W min = Minimum FIG. 1 JANUARY 1987 TO IS : 4995 ( Part 1) . bulk density of the stored material.3. ( Page 13.3.3 Bins for storage of powdery materials are often equipped with devices for pneumatic emptying and when these devices are used for aeration of stored material. loosening of the material in the region of the outlet occurs. India .3.3.2) ‘ AND ASSESSMENT A.k1. clause 6.1974 CRITERIA FOR DESIGN OF REINFORCED CONCRETE BINS FOR THE STORAGE OF GRANULAR AND POWDERY MATERIALS PART 1 GENERAL REQUIREMENTS OF BIN LOADS ( _ ( page 10. clause 6.3. (BBC381 Printed at Simco PrintiPress. Delhi.in the the following for the existing figure: NORMAL EMPTYING --NORMAL FILLING PRESSURE 1.3 ) -Substitute clause: ‘6. 4 ) Substitute L- ~-z~. Note ) informal table given in the Note. Fig. no significant increase in load due to the air supply has so far been detected.MENDMENT First Revision ) - Substitute the following for the existing formula: z c P.NO.=TDWR 0 ( Page 12. clause 6. In this case.(l--e-~‘= Add ‘m/h’ as unit under V.2. 4 PREWJRE SCHEMEDURING PNEUMATIC EMPTYING the following for the existing ( Page 15.