Lateral pressure on a wall from a grain pile 2

[nivoo_boss]

Hey everyone!

So I have this structure where grain is going to be piled against the bay walls. The walls are 3 m high. Try to ignore the simple wall and floor on the drawing, I'm only looking for help to determine the lateral load on the walls from the grain.

My local engineer's handbook gives an average density for grain 8 kN/m³ and an angle of repose of 30°. Perhaps you guys have some experience on what sort of lateral pressure coefficient I should use for a material such as grain? On the drawing I used the usual Rankine's active lateral pressure coefficient for soils, but I'm not sure how appropriate it is for grain.

Anyway, the drawing is below. Any help is appreciated.

 

[Klitor]

I use 'at rest' in those situations.

 

[human909]

I agree with Klitor. Also for recommended values for bulk solids it is a good start to refer to :
EN 1991-4 (2006) (English): Eurocode 1: Actions on structures - Part 4: Silos and tanks

Pa

 

[nivoo_boss]

Great, thanks!

 

[1503-44]

Thanks for that handy table.

A black swan to a turkey is a white swan to the butcher.

 

[dik]

ditto...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Brad805]

I have seen this type of structure used for fertilizer storage, but it is uncommon for grain. Do you know the grain types? The at-rest coefficient will be fine for dry grain, but if this facility handles any wet grain like is common in at harvest time it might not be.

 

[JoelTXCive]

ACI also has a manual on grain silos that might help: ACI 313 Standard Practice for Design & Construction of Concrete Silos & Stacking Tubes for Storing Granular Materials.

I think there are older versions (1997) available for free on the net.

Instead of Rankine, they reference a Janssen's Method. (I'm not familiar with that)

 

[dik]

If you hurry... found a 313-16 version...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JStephen]

If by chance, they'll be scooping material out with a front-end loader, vehicle impacts may control design. There have been some past topics on that.
There is a silo design handbook by Gaylord and Gaylord. In one place, they say "So-and-so recommends using this equation and these coefficients." Then a couple of pages over, "But so-and-so recommends THESE equations and coefficients." And if you ran the numbers, they came out considerably different between the two approaches. The lesson learned is that some of this stuff is not as exact as you might suppose.

 

[human909]

Instead of Rankine, they reference a Janssen's Method. (I'm not familiar with that)

Janssen is more suitable for products restrained in four sides. (Or more commonly, a single cylindrical walled silo.) It is an approach that I regularly use. It accounts for the reduction in vertical pressure due to friction with the side wall. Eg, vertical pressue and lateral pressure is not linear with height.'

This is a good paper comparing codes for different regions. As discussed in this paper and I agree, the Eurocode EN 1991-4:2006 is the most advanced structural code for bulk material storage. It isn't a bad start whatever your locality.

If by chance, they'll be scooping material out with a front-end loader, vehicle impacts may control design.

Agreed. Using a passive earth pressure approach would get higher numbers but will cover you for vehicles pushing material against the wall. Actual vehicle impacts well that is a judgment call on robustness sevicability.