Janssens Formula and Unit Weight of Grain 1

[lovethecold]

I am looking for a book that has a good description of Janssens Formula for circulat tanks. I am hoping for a good explanation of theory as well as application. The latter being most important. The method we use has different variables than the one a structural engineer uses. Our values differ by 50%.

Also, can anyone give me a good rundown on the unit weights of grain (compacted and uncompacted)? Would like pounds per bushel as well as pounds per cubic foot. Metric units is fine. Mostly grain bins and silos we deal with use wheat, corn, beans, sugar, sunflowers, and flax. We base our calculations on wheat. I understand that wheat is the heaviest grain we have. We use 50pcf for wheat, the structural engineer is using 57 pcf, a web search shows values ranging from 46 to 50 pcf for wheat.

I just want to get a handle on this, grain bins have been dramatically increasing in size. There is becoming a problem with soil capacity and settlement.

Thanks in advance for the assistance.

 

[lovethecold]

I just found out the reason for the difference. Apparently the structural engineer is using a correction factor. This correction changes Janssens results to correlate with the results of another method.

I would like to know the what the other method is, and how to use it, if there are any other ideas as to what it is. I will try to find out who this other engineer is and get the details.

Thanks.

 

[BigHarvey]

wheat 750 to 760 kg/m3
oats 410 to 540 kg/m3
corn 670 kg/m3
barley 600 to 700 kg/m3
rye 685 to 790 kg/m3

hope it still helps !

 

[BigH]

http://www.powderandbulk.com/resources/bulk_density/material_bulk_density_chart_r.htm

and then use like a dictionary.

 

[connect2]

I have a copy of a translation of the original Janssen Paper 'Experiments in Corn Pressure in Silo Cells', Aug 31st 1895, including original fig's. The experiments he performed are great, and the basic formula still in use today!

 

[BigH]

Perhaps you can request SlideRuleEra to put on his website? He is putting on a lot of the "old" stuff. SRE??

 

[jheidt2543]

Here is a link to a PDF of the paper:

http://arxiv.org/PS_cache/cond-mat/pdf/0511/0511618v1.pdf

 

[BigH]

Jim - thanks to see you back!! Terima kasih for the link!

 

[connect2]

jheidt2543,
Perfect. I often print articles off the internet and so long as they have a reference otherwise haven't a clue where i got them. This paper is an essential for those of us designing bins and silos, it is infact the starting point despite the fact that Janssen took advantage of others previous work in this area at the time.

 

[BigH]

connect2 when I download papers off the net, I usually (try almost always) to copy the URL to a "Note" comment that I put on the efile pdf copy. This way you can always find the URL again. Just a thought.

 

[lovethecold]

Thank you jheidt2543 for the link. Very interesting paper, I like reading the theory behind the formulas. Thanks for the tip BigH.

 

[connect2]

BigH, good idea. I have much to learn about electronic filing and files.