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coef. of friction on corregated galvanized bin wall
i am looking at a foundation for a 48 foot diameter corregated galvanized bin which will store navy and pinto beans. i need a friction coef on the wall from the beans to determine the wall friction load on my foundation. does anyone know where i can get this value from? thanks
acoona, start your search with the american society of agricultural engineers, should get you the coeff. of friction for your particular products. i'll reference the following paper as well .. (trying to watch my english english here) ...
'cold-formed steel farm structures part i: grain bins', g.abdel-sayed, f. monsa, w.siddall, asce jrnl. of sruct. engineering, vol. iii, no.10, p.2065-2089, oct. 1985. an excellent reference section as well. the portion of the total load carried by the corrugated wall is different than normal walls, ie concrete of steel, due to the corrugations, all else being equal, anyways it is discussed in the paper.
australian standard as 3774-1996 ("loads on bulk solids containers") has a method for calculating the effective coefficient of friction when the corrugations run horizontally. (for vertically corrugated sheeting, you use the same coefficient as for flat wall sheeting, because the corrugations do not significantly impact on material flow.)
basically, you calculate the wall friction coefficient for a flat wall, and also the internal friction coefficient for the material being handled; then you take a weighted average, considering how much of the flowing material will slide against the tops of the wall ribs which project into the bulk material, and how much of the bulk material will slide against other bulk material which is "trapped" in the valleys of the ribs.
mu eff = u2.mu i + u3.mu w
where:
mu eff = effective wall friction coefficient
mu i = internal friction coefficient = tan (phi i)
mu w = wall friction coefficient for a flat wall surface = tan (phi w)
and u2 and u3 represent the proportions of the bulk solid moving against itself and moving against the wall sheeting (such that u2 + u3 = 1.0).
for a typical corrugated sheet profile, u2 would be of the order of 0.67 to 0.75 say, with u3 being approximately 0.33 to 0.25 accordingly.
hope this helps!
navy beans bulk density 48-54 angle repose up to 30
from "useful info on the design of steel bins & silos" aisc

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