Silo load

[Pawel27]

I have structure filled wit ash like in attachment. I am considering silo load from this ash. Unfortunately all books, codes, publications doesn't consider structure like this.
There is only vertical wall and hopper below. In my structure there is also next vertical wall (called by me "2nd vertical wall") below hopper. I would like to calculate pressure load. I am looking for book, publication or any code with similar geometry. Any comments will be also appreciated. I am preparing Drucker-Prager model in FEM analysis, but I would like to have also
some theories.

 

[paddingtongreen]

No attachment!

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[BAretired]

What attachment?
I believe the Canadian Farm Code lists pressures of various bulk storage materials. Here is another reference

BA

 

[Pawel27]

This is problem with defining pressure distribution below level A.

 

[JStephen]

Can't really help with the specifics, and if you've researched the literature, you know as much about the theory as I do.

I will point out two things, though. First, is that in the past, using Gaylord and Gaylord's silo book, they gave multiple approaches for standard silo loading, and using alternate approaches that were apparently equally valid gave very large variations in the calculated pressure, indicating that those approaches are all very approximate at best.

Secondly, if any kind of silo is small enough, you can make some conservative assumptions about loading and greatly simplify the design. For example, treat the product as a fluid and design for that hydrostatic pressure, then treat the product as though it were all stuck to the walls, and design for that vertical pressure on the walls. For a large silo, this will be overly conservative, but for smaller ones, it is a worthwhile simplification.

I took one of ASME's courses on flow of solids a while back, and found it of interest. The presenters were from Jenike & Johanson, and they do consulting on exactly this type of problem.

http://www.jenike.com.

 

[Brad805]

The Eurocode might be helpful to define your loading scenario. They have the most well defined codes out there.

From JM Rotter, "Guide for Economic Design of Circular Silos," Eurocodes [CEN ENV1991–4, 1995; CEN ENV1993–4–1, 1999; CEN ENV1993–1–6, 1999]. I know yours is not circular, but from the discussions in the book I believe the eurocode does address your situation. I also found some of the top researchers at:

http://forum.bulk-online.com/forum

Brad

 

[Pawel27]

I know EN 1991-4. There is only vertical wall-hopper scheme. Not vertical wall below hopper. Vertical wall below hopper is what I am interested in. Thanks Brad for forum:

http://forum.bulk-online.com/forum.

I know this forum, but I didn't find answer in posts on my question.

JStephen - this is quite big structure. Total height h about 15-20 meters. Linear theory seems to be not adequate. In fact this is even not so important in my question
whether we consider linear or nonlinear theory. Ok, so maybe I precise my questions to below considerations:

We can focus on next picture below. I have some matters basing on it:
1.) Stripped area is let's say "dead area". Question is what is influence of this "dead area" on normal pressure value p1 and p2. In calculations p1 and p2 I should take straight rectangular with dimensions a*h or consider also this dead area.
2.) What with eventual pressure perturbation at level A. Below this level pressure p2 diminish to value p1 or p2 keep value p3 (from perturbation)

Two possible pressure distrubition for next considerations in attachment

 

[Brad805]

Sounds like you may need some specialist advice from the guys working on the codes with the Europeans. I have talked with engineers at

http://www.jenike.com/Company/locations.html,

and they were very helpful.

Brad

 

[Pawel27]

It would be nice to solve the problem alone with some help at this forum ;-)

 

[paddingtongreen]

Your "dead area" will be pretty much dead except the interface will be sloped at approximately the angle of repose. If your material is bottom ash, it may bridge at the top of the lower parallel wall.

I don't know the logic of your pressure diagrams, it looks like the Janssen formula all the way on the left wall. On one side it looks like funnel flow with mass flow on the other. I have no idea how to work that.

Michael.
Timing has a lot to do with the outcome of a rain dance.