Grain Pressure Equivalent Fluid Density
Grain Pressure Equivalent Fluid Density
(OP)
I am looking for some other opinions/information on how grain pressure along a perimeter wall, such as a flat storage building, should be calculated. In the past I have used Rankine's equation for active earth pressure with a backslope in determining the equivalent fluid density. If I were to assume angle of repose of 25 degrees, angle of internal friction of 25 degrees, and a unit weight of 52 pcf the equivalent fluid density calculates out at 42.4 pcf. However I have come across an article that states that the equivalent fluid density for peaked corn is 23 pcf (see pg 2 of link below for article).
Does anyone know how the author came up with this value? Any help would be greatly appreciated.
P.S. The author doesn't reference where his values were obtained and I emailed him asking and did not receive a response.
http://www.ag.ndsu.edu/graindrying/publications/ae...
Thank you.






RE: Grain Pressure Equivalent Fluid Density
RE: Grain Pressure Equivalent Fluid Density
Start research with this PDF.
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: Grain Pressure Equivalent Fluid Density
Luckily, I've never had to use it.
RE: Grain Pressure Equivalent Fluid Density
I'm not saying this is right and the way to do it, just pointing out a possible source.
One issue with Gaylord & Gaylord's bin book is they'll give you three different ways to figure the pressure and you get three completely different answers when you do, which tends to turn it from science to voodoo.
RE: Grain Pressure Equivalent Fluid Density
JStephen in case I can't find the book does it mention whether the values they are providing take into account backslope?
Thanks.
RE: Grain Pressure Equivalent Fluid Density
This is on the bottom of Page 22-4 in the Second Edition, if that helps.
RE: Grain Pressure Equivalent Fluid Density
My old office had two versions. The older edition had much simpler methods, but something tells me you might be found to be practising behind the state of the profession if you don't use the new methods.
RE: Grain Pressure Equivalent Fluid Density
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: Grain Pressure Equivalent Fluid Density
RE: Grain Pressure Equivalent Fluid Density
It provides a values that are slightly less than the Rankine equation I was previously using.
Might be in line with the Gaylord and Gaylord book which used the centroid of the sloped height for the equivalent grain height but I didn't have that resource.