Equivalent Fluid Pressure 1

[dmoench1]

I work for a company that does a lot of storage buildings. Many times these builidngs have concrete walls that retain fertilizer (all types), grain and salt/sand storage. What resource can I turn to to get the most accurate values for evaluating the pressure imposed by the material on the walls? I've used the old Midwest Plan Service book for grain but what about the other materials? Because I work for the company that supplies the building as well as the foundation I'm looking at applying the most accurate numbers without being too conservative with the design.

Thanks

 

[SteveGregory]

Check out a copy of "Structural Engineering Handbook" by Gaylord & Gaylord or a similar handbook and see if there might be a table of values for those materials.

 

[dmoench1]

SteveGregory,

Thanks for the suggestion. I used to have that book but lost in when I changed jobs a few years back. I guess I can pick up a used copy of it.

 

[weab]

I have used a book named, I believe, Theory of Tubular Structures by Troitsky. Forget the name, it fully describes the loading of rectangular steel structures.

With that said, this book is likely a close second if you don't have Gaylord & Gaylord.

 

[IDS]

Be careful!

This isn't my area, but I know that storage structures can be subject to much higher lateral pressures than expected because of thermal ratchetting.

Link with a brief description:

http://concreteproducts.com/mag/concrete_silo_design/index2.html

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[JStephen]

Don't expect to get really accurate numbers for the pressure. You'll find stuff like "Author A recommends this coefficient, Author B recommends this coefficient, and Code Z requires this coefficient", and it'll give you three completely different values. If it's a building being used for bulk storage, I assume you'd also have front end loaders banging around in there, so it's not a time to be too conservative.

Gaylord and Gaylord also wrote a book specifically on bins and silos, and if you're shopping for used books, look for it. I think John Buzek has a silo book available through the Steel Plate Fabriators Association.

 

[dmoench1]

Hey everyone,

This has been helpful but I should clarify that this is not a steel bin. This is a steel truss building with a fabric membrane roof. Additionally it has reinforced concrete walls of up to 10' in height retaining the products mentioned in the first post. Very often the endwalls of these buildings are open so thermal changes aren't so much a concern as what humidity does to the product. With all that said, I would be happy to pick up any of the books that have been referenced but they are all fairly expensive so it would be nice to know if the information I seek is actually in the books you mention. Specifically, what is the Equivalent fluid pressure exerted on a vertical surface from urea, dap, potash, salt/sand mixtures, grain, etc. If you have seen it in a book that is all I need to know to buy the book.

Thanks again,

 

[CTW]

I'm assuming that you basically have bins with concrete walls on three sides. The force of the loader will control the design, so that should be the starting point. Then possibly check the wall for the product pressure since the walls are 10 ft tall.

This is not the time to sharpen your pencil. Some reasonable amount of conservatism needs to be built into the design as the loaders will beat the walls to death.

Maybe there is something published by the agricultural industry that may help. You may be able to find material densities and angles of repose.

http://www.mpd-inc.com/material.htm

 

[dmoench1]

CTW,

Duly noted about the loader loads. I did open the attachment and it had great densities of product but no repose angles or EFD values. The search continues.

Thanks again

 

[SlideRuleEra]

dmoench1 - Try "tracking down" your materials one-at-a-time. For example, here is a reference that gives the angle of repose of grain as 25 degrees (perhaps you may find other values, too).

http://lancaster.unl.edu/ag/crops/inservice/outside.htm

Here is one for salt (32 degrees) and for sand (also 32 degrees).

http://www.dome-corp-na.com/sand.html

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[dmoench1]

SlideRuleEra,

Those pages were great. The only thing missing was the calculation for pressure against the retaining walls. Is there a quick formula that I'm not aware of that if you have the material weight and angle of repose that you can determine the pile pressures against vertical retaining surfaces?

 

[SlideRuleEra]

You could use the basic Rankine, Coulomb methods to incorporate angle of repose into the equation to get an equivalent fluid pressure for the material of interest. See the information starting on page 5 of "US Steel Sheet Piling Design Extracts" which can be downloaded (free, as is everything there) from this page of my website:

http://www.slideruleera.net/Steel-Piling.html

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[JStephen]

If I remember correctly, those reference books recommend to test actual samples to determine the different material property values.

If this is material you're buying, you might check with suppliers for information.

 

[dmoench1]

SlideRuleEra,

Thanks for the pdf that is exactly what I needed. Thanks to everyone else for your valued insights.

dmoench

 

[Gumpmaster]

Try "Assessing Loads on Silos and Other Bulk Storage Structures" by Geoffry Blight.

Google books has a preview. It appears to offer what you're looking for.