MWMAW‘Y—Nm Immcmmnuo MHMMdll WSTAYICOLLIGI W.W.M 1943 THE-515 The Design of a Cast-In-Flace Reinforced Concrete Silo A Thesis Submitted to The Faculty of IICHIGAN STATE COLLEGE of A RICULTJRE AND APPLIED SCIEYCE by W. W. Sewell my.“ Candidate for the Degree of Bachelor of Science June 1948 THEJSRE L.’ INTRODUCTION The value of silage and chOpped grass as a principle source of vitamins, minerals, proteins, and bulk for livestock, proves conclu- sively that silos are a ”must" in the future of modern farming. This food value and the resulting demand for same, has encouraged our agricultural implement manufacturers to design and perfect up-to-date ensiling machinery. Many of the countries leading manufacturers such as John Deere, International.Harvester, Case, Allis-Chalmers, and For new display and sell a complete line of cutting, loading, haul- ing, and filling equipment. ‘ l The results of increased silage production has deveIOped the trend to construct larger and more modern silos. A modern silo has as its primary function; the economical preservation of silage. It must be durable, as well as, be rot, rust, fire, and storm resisting. Moreover, it must furnish many years of 10Ibcost storage. After carefully considering the governing factors listed in the preceding paragraph, the Author has chosen twin east-in-place concrete 51109 with steel reinforcement, and to make this problem more re- alistic the Author will design the twin silos to eventually replace two tile silos badly damaged by fire several years ago. The farm is known as the Twin Brooke Farm located in Washington TOUDShip, Macomb County, Michigan. 1‘2 31.71 ACIQIOWIJLLDGU TEDTT I wish to express my gratitude to Professor C. M. Cade of the Civil Engineering Department Michigan State College for his valuable assistance and helpful advice. The All thor e DIAMETER The usual practice is to select a silo of such diameter that 2 or 3 inches can be removed daily to avoid spoilage. Two silos are desirable in this case; one for grass and one for corn silage. The feeding ratio is to be approximately 40# of grass and 40# Of silage daily to each of 30 dairy cows. This makes a total of 1200# to be removed from.each silo daily. Design: Try 16' with 2" removal daily 3 16 ' 16 0 3.1416 g 210 Ft. 4 3 210 ' .1666': 33.55 It. 3 33.55 . 40# per Ft. : 1340# 3 Based on an average weight of 40# per Ft. this diameter is too large since we are removing only 1200# daily and not 1340# Try 14' with 2" removal daily 3 l4 - l4 ' 3.1416 '1 3 25.7 Ft. 4 6 3 25.7 ' 40# per Ft. 3 1028# This diameter will suffice since a 1200# daily removal will more than insure the minimum 2" spoilage limit (1028#) (1) HuIGBT It is practical, in Xichigan, to design silos for at least a minimum 200 day feeding season. Design: 3 3 40# per day per cOW'G 40#per Ft. for 30 head is a 30 Ft. per day 3 removal. A 14' silo would have a volume of 154 Ft. per foot of height. Height required 3 50 ' 200 = 40' 154 (2) SE’ECIFI CATI 'oNS 2 1. The allowable stress in steel is to be 20000# per In. for intermediate grade steel bars conforming with the 1940 Report of the Joint Committee of Standard Specifications for plain and reinforced concrete. 2. The cement for use must conform to the current specifications of the American Society for Testing'Materials (ASTMJ. 3. The concrete must have a high degree of imperviousness and durability to slow the action of silage acids. The minimum compress- ive strength at 28 days should be: footings 3000 psi., for silo walls, roof, door frames, and chute 4500 psi. To attain this strength the water-cement ratio of the footings should be less than .734 and for all other parts .677. 4. The weight of silage varies as the depth and in direct pro- portion to the water content. For a 40' silo the weight varies, on the average, from 20# per Ft? at the tOp to 65# per Ft? at the bot- tom. 5. Data for the lateral pressure and vertical friction pressure computations which follow was obtained from a research study in which the United States Department of Agriculture, The New Jersey Agricul- ture Experiment Station, The National Association of Silo Manufactures, and The Portland Cement Association c00perated. The work was done at the Dairy Research Farm at Sussex, New Jersey. (3) SPECIFICATIONS 9331. This comittee's work showed, (1) that the relation betIeen lateral pressure and head of silage is expressed as a curved line, and (2) that there is no justifieation for assigning different pressures to different ensiled materials. The data indicates clearly that lateral pressures increase with moisture content and with the diameter of the silo. 6. The allowable soil pressure on a sandy soil is 8000 # per It?" 7. Since Juices of legume and grass silages are more strongly acid than normal corn silage, it is advisable to apply a frequent protective coating to the inside surface of silo walls. here are several good treatments available, one of whichm-Linseed Oil- will be described here.* Linseed 9.1; Treatment. Concrete silo walls should be thoroughly ' [s " cleaned and dry before application of the linseed oil. Boiled lin-QV 5011' ; seed oil is generally used because of its quicker drying prepertiesJL‘ILI/pt 5“) For the first coat the oil should be thinned with equal parts of A‘s“ i. :12») ‘I turpentine to give increased penetration. Allow this coat to dry I v (411/ " ’ a .1 ’ 3/: . . a a 'I s O . . x . thoroughly before applying the second coat. The second coat is app- )' 4.10),? E .f \- , . lied without thinning. Spots where the oil has been absorbed should «f '5 r ' be given additional costs. The last cost should be allowed to dry for at least 8 weeks before the silo is filled. One gallon of lin- 2 seed oil will cover about 200 It. -- 2 coats. (4) ‘ Concret. Infomtq m. \Tn I'I'DAA nA_L1__.1 11-..-..a a---lj-a1. FOOTING Design loads 1. Weight of 1 foot on mean circumference for entire height of 40'. 2 Area of 15' circle; 177.1 Ft. 2 Area of 14' circle- 154.05 Ft. -u.______ 2 Area of hOOp 3 23.05 Ft. 3 Vblume of hOOp 40' high--23.05 - 4O : 922 Ft. 3 922 3 20.2 Ft. per ft. of mean circumference 3.1416 0 14.5 20.2 ' 150 g 3030# per ft. of mean circumference 2. Vertical friction load of silage is based on experimental work (see above) where various samples under different moisture con- tents are used and the relation between depth and vertical pressure measured. This data is plotted graphically and a curve is found by least squares to fit these values. The equation f: 5.5 h1.oawhere f 3 vertical wall load inpsf and h = depth below t0p of silo in feet, is the best fit under these conditions. Since the maximum.pressure is needed at the base of the footing it is found by intergrating from O to h the equation above; h 1.03 2.08 2.08 F g / 5.5 h g 2.64 h where h . 40 and h g 2149 0 2.08 F a 2.64 h = 5673.4# per ft. of circumference P : allowable soil pressure and W = width of footing in inches. (5) FOOTING Cont. Width Design W : 12 (5673.4 { 30391 g 13” ‘P Depth Design Shear is not a limiting factor in the design of silo footings hence the depth of plain footings should be calculated by the foll- owing formula; d 3 .Z P W where d 3 required depth, W: width of footing 131 2 in inches, and P : allowable soil pressure in # per It. a g [8000 - 13 . 8.89 use 9" 131 The weights of the roof, chute, reinforcing steel, footing, and foundation.wall were omitted in computing the footing dimensions. The increase in width of the footing due to the above mentioned would amount to about 6k%. Considering the uncertainty as to the allowable soil pressure, the author feels that sufficient accuracy is obtained by use of the vertical friction pressure and the weight of the wall. (6) 4‘1 Ccncrete bye and ger.it easier cl» 'in;. I: t::s 'e'i * a Will be usni with a slight slo e t; :ds a cent-); is located in Tgé C€*§er of the f1 «r is constructed [)5 to a free outlet. The floor slw.‘ movement relative to the walls whi: allots silsre ‘mh 5 .4. 4‘ out tryouxng its silo out of f Thg1rall chosen here is to be a" thick ccntai ‘\ 2“”Plvr Of a?! htfid below. .: " g. _ .. ‘. ally in the center of tns will at ;uiiz-ntai rods of 1:3 It,. rel ize ayi r a wall thickness 3 011‘ 4‘ 4 “kW 4 *9 used to :he horizvrtal stevl. ans co'mittee ath Im a so v. sead Of . “:1. . and by r‘: a monk; - Concrete ere “Hart‘flfil pres d19117h9 in feet from % :1 ,— . I m \\ 10‘73 e at m:ic“~» lui' - '; hit 59, 3 (M) 4re of either r Im,lrr ‘ (L- '1 A 4 O .a‘-i.:~ ‘ a'l the tug tff silo. 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