1、 ANSI/ASAE EP446.3 APR2008 (R2012) Loads Exerted by Irish Potatoes in Shallow Bulk Storage Structures American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicable to agri
2、cultural, food, and biological systems. ASABE Standards are consensus documents developed and adopted by the American Society of Agricultural and Biological Engineers to meet standardization needs within the scope of the Society; principally agricultural field equipment, farmstead equipment, structu
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6、ards, Engineering Practices and Data approved after July of 2005 are designated as “ASABE“. Standards designated as “ANSI“ are American National Standards as are all ISO adoptions published by ASABE. Adoption as an American National Standard requires verification by ANSI that the requirements for du
7、e process, consensus, and other criteria for approval have been met by ASABE. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simpl
8、e majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. CAUTION NOTICE: ASABE and ANSI standards may be revised or withdrawn at any time. Additionally, procedures of ASABE require that act
9、ion be taken periodically to reaffirm, revise, or withdraw each standard. Copyright American Society of Agricultural and Biological Engineers. All rights reserved. ASABE, 2950 Niles Road, St. Joseph, Ml 49085-9659, USA, phone 269-429-0300, fax 269-429-3852, hqasabe.org ANSI/ASAE EP446.3 APR208 (R201
10、2) Copyright American Society of Agricultural and Biological Engineers 1 ANSI/ASAE EP446.3 APR2008 (R2012) Revision approved May 2008, reaffirmed February 2013 as an American National Standard. Loads Exerted by Irish Potatoes in Shallow Bulk Storage Structures Developed under the direction of the SE
11、-202 Committee of the ASAE Structures Group; approved by the ASAE Structures and Environment Division Standards Committee; adopted by ASAE as a Data February 1985; reconfirmed December 1989; revised and reclassified as an Engineering Practice August 1990; revised November 1995; approved as an Americ
12、an National Standard December 1995; reaffirmed January 2001; reaffirmed by ANSI January 2001; reaffirmed by ASABE February 2006; reaffirmed by ANSI March 2006; editorial revision September 2006; revised April 2008; revision approved by ANSI May 2008; reaffirmed by ASABE December 2012; reaffirmed by
13、ANSI February 2013. Keywords: Loads, Potatoes, Pressure, Storage 1 Purpose and Scope 1.1 This practice provides guidelines from which designers may calculate loads on vertical and inclined walls, partitions, bin fronts, ducts, and appurtenances that are to resist lateral pressure of potatoes stored
14、in bulk. These guidelines may be modified for specific, unique load conditions. 1.2 This practice is for bins that are wider than deep (B H) and not deeper than 5.5 m (18 ft) (see figure 1 for explanation of symbols). 1.3 This practice is for bins in which length (L) is greater than width (B). 1.4 T
15、his practice applies to maximum potato pressures measured in full-sized bins. These occurred with wet potatoes. 1.5 Other types of structural loads are listed in the following standards: ASAE EP475, ASAE EP378.3, ASAE EP538 and ASAE EP545. Figure 1 Bin layout with symbol representation showing dimen
16、sions and angle of internal friction (repose). (See clauses 1, 4, 5 and 6 for explanation of symbols.) ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engineers 2 2 Normative References The following standards contain provisions which, through reference in
17、this text, constitute provisions of this Engineering Practice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Engineering Practice are encouraged to investigate the possibility of applying the most recent
18、editions of the standards indicated below. Standards organizations maintain registers of currently valid standards. 2.1 ASAE EP475.1 JAN01, Design and Management of Storages for Bulk, Fall-Crop Irish Potatoes 2.2 ASAE EP378.3 FEB04, Floor and Suspended Loads on Agricultural Structures Due to Use 2.3
19、 ASAE EP538 DEC1996, Design Loads for Bunker (Horizontal) Silos 2.4 ANSI/ASAE EP545 MAR1995, Loads Exerted by Free-Flowing Grains on Shallow Storage Structures 3 Terminology 3.1 potatoes, dry: Potatoes put into the bin under normal harvesting moisture conditions without being sprayed with water and/
20、or chemical fungicide or rained on. 3.2 potatoes, wet: Potatoes that have been sprayed with water and/or chemical fungicide or have been rained on during bin filling operations. 3.3 storage, potato: A structure designed and constructed for storing potatoes in bulk. 4 Nomenclature h is overall height
21、 of potato pile, m (ft) z is distance below top of potato pile, m (ft) g is acceleration due to gravity, 9.81 m/s2(1 lbf/lbm) m is mass of the product per unit volume, kg/m3( lbm/ft3) Kais active pressure ratio of lateral to vertical stress C is vertical distance from bottom of pile to the resultant
22、 force of the pressure p H is height of bin wall, m (ft) p is perpendicular pressure caused by the potato pile acting on the wall per unit area of vertical wall surface, kPa (lb/ft2) S is summation of frictional force from potato pile acting on the wall surface and in a direction parallel to the wal
23、l surface for a unit height of wall, kN/m (lbf/ft) W is resultant of the wall pressure, p, from potatoes, acting perpendicular to wall face, for a unit length of wall, kN/m (lbf/ft) is angle included between bin wall and bin floor, which is covered with potatoes, degrees is internal angle of frictio
24、n of the stored material, degrees ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engineers 3 is angle of friction between the stored material and the wall, degrees = tan is coefficient of friction between wall surface and stored potatoes, at rest, dimensio
25、nless 5 General Design Information 5.1 angle, inclined wall (): This normally is less than or equal to 90 degrees and greater than . 5.2 density, bulk (m): The bulk density of potatoes may range from 625 kg/m3(39 lb/ft3) to 700 kg/m3(44 lb/ft3). Large potatoes greater than 89 mm (3.5 in.) diameter w
26、ith a low specific gravity of 1.050 may reach the smaller bulk density value. Small potatoes less than 50 mm (2.0 in.) diameter with a high specific gravity of 1.100 may reach the larger bulk density value. A bulk density of 670 kg/m3(42 lb/ft3) is normally used for field-run potatoes. 5.3 friction,
27、 angle of internal (): For potatoes, the angle of internal friction, , is approximated in practice as the filling angle of repose of the product (see figure 1) and may range from 26 to 36. An average value is 32. 5.4 friction, static, coefficient for surface (): Use values for the static coefficient
28、 of friction shown in table 1. 5.5 wall pressure: Potato pressure normal to the bin wall at depth z, p(z), is given as an equivalent liquid pressure p(z) = Kam g z (1) The active pressure ratio Kais ()22sinsinsinsinKa+= (2) Figure 2 compares a typical measured pressure loading and an equivalent liqu
29、id pressure loading calculated by equation (1) for a bin. For design purposes an empirically derived pressure was based on an angle of repose of 31.5 and a density of of 670 kg/m3(42 lbm/ft3). See figure 2. Figure 2 Typical measured potato pressure curve with calculated pressures, (p), for a shallow
30、 bin ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engineers 4 5.6 force, center of (C): The center of force, C, is one third the pile height, h, from the bottom of the pile (see figure 3). C = h/3 Figure 3 Free body diagrams of bin wall (see clause 4 for
31、 explanation of symbols) 5.7 force, total lateral (W): Total lateral force, W, is calculated using the following equation W = p(h)h / 2 (3) where p(h) equals p(z) in equation 1 for z = h. 5.8 force, total axial (S): The total axial force due to the potatoes, S, is calculated using the following equa
32、tion S = W (4)6 Example Calculations 6.1 Vertical wall: 6.1.1 Given: h = pile depth = 4.8 m H = wall height = 5.4 m C = center of force = h/3 = 4.8/3 = 1.6 m = 90 6.1.2 Assume: m = 670 kg/m3 = 32 = 0.48 (smooth concrete) 6.1.3 Calculate pressure ratio Kaby equation (2): Ka = sin2(90 32)/sin90(sin90
33、+ sin32)2 = 0.3073 6.1.4 Calculate pressures: Pressure at depth z by equation (1): ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engineers 5 p(z) = 0.3073 9.81 670 z = 2020z N/m2= 2.02z kN/m2Pressure at bottom of wall, z = h p(h) = 2.02 4.8 = 9.70 kN/m26.
34、1.5 Find total lateral force (equation 3): W = p(h)h/2 = 9.70 4.8/2 = 23.3 kN/m 6.1.6 Find total axial force (equation 4): S = W = 0.48(23.3) = 11.17 kN/m 6.2 Inclined wall: 6.2.1 Given: H = pile depth = 4.8 m H = wall height = 5.4 m C = center of force = h/3 = 4.8/3 = 1.6 m = 75 Table 1 Static coef
35、ficients of wall friction for potatoes on various surfaces. Averaged for wet and dry potatoes. Surface Coefficient, Steel, corrugated, galvanized (across corrugations) 0.70 Rough concrete 0.59 Potatoes 0.57Plywood (with grain) 0.52 Rubber belting 0.50 Smooth concrete 0.48 Steel, smooth, nongalvanize
36、d 0.43 Steel, galvanized 0.43 Polyethylene sheet 0.39 ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engineers 6 6.2.2 Assume: M = 670 kg/m3 = 32 = 0.48 (smooth concrete) 6.2.3 Calculate pressure ratio Kaby equation (2): Ka = sin2(75 32) / sin75 (sin75 + s
37、in32)2 = 0.2152 6.2.4 Calculate pressures: Pressure at depth z by equation (1): p(z ) = 0.2152 9.81 670 z = 1414z N/m2= 1.414z kN/m2Pressure at bottom of wall, z = h p(h) = 1.414 4.8 = 6.79 kN/m2(70% of the pressure on the vertical wall) 6.2.5 Find total lateral force (equation 3): W = p(h)h / 2 = 6
38、.79 4.8 / 2 = 16.29 kN/m 6.2.6 Find total axial force (equation 4): S = W = 0.48(16.29) = 7.82 kN/m Annex A (informative) Bibliography The following documents are cited as reference sources used in development of this Engineering Practice. Edgar, A. D. Pressure on walls of potato storage bins. USDA,
39、 Agricultural Marketing Service. AMS-401; 1960 Lambe, T. W. and R. V. Whitman. Soil mechanics. John Wiley and Sons; 1969 Permanent Wood Foundation System Manual. National Forest Products Association; 1987 ANSI/ASAE EP446.3 APR208 (R2012) Copyright American Society of Agricultural and Biological Engi
40、neers 7 Powell, A. E., C. A. Pettibone and M. R. Torabi. Pressure exerted on walls of larger bins by stored potatoes. Transactions of the ASAE 23(3):685-686; 1980 Schaper, L. A. and E. C. Yaeger. Horizontal and vertical pressure patterns of stored potatoes. Transactions of the ASAE 25(3):719-724; 19
41、82 Schaper, L. A. and E. C. Yaeger. Accuracy of equivalent fluid pressure for potato storage wall design. Transactions of the ASAE 26(1):179-184, 187; 1983 Schaper, L. A. and E. C. Yaeger. Coefficients of friction of Irish potatoes. Transactions of the ASAE 35(5):1647-1651; 1989 Schaper, L. A., K. G
42、. Janardan, E. C. Yaeger and P. H. Orr. Mathematical expressions for lateral potato pressures. Transactions of the ASAE 32(3):1075-1080; 1989 Torabi, M. R. Pressure exerted on the walls of large bins by stored potatoes. Unpublished M.S. thesis, Washington State University, Pullman; 1976 Willson, G.
43、B. Lateral pressures on walls of potato storage bins. USDA, Agricultural Research Service. ARS 52-32; 1968 Yaeger, E. C. and G. L. Pratt. Instrumentation for measurement of lateral and vertical pressures in potato storages. Transactions of the ASAE 20(6):1180-1184; 1977 Yaeger, E. C., L. A. Schaper and P. H. Orr. Comparison of potato pile pressures on vertical and inclined walls. Transactions of the ASAE 30(6):1811-1816; 1987
