Offset Loading of Silo
Offset Loading of Silo
(OP)
I am working on a project to add a new circuit to the top of a 50’ diameter 110’ tall concrete silo. Client has asked about installing a stone ladder (material is hydrated lime) on the side wall. The original design is center loading of the silo and I think moving the loading to the side wall will cause bending moments in the wall since the material will be much higher on one side than the other. Angle of repose is around 45 degrees so loading on the side wall will mean a material height difference of 50’.
I can’t find a simple equation in silo design references to address this issue so my plan is to make an FEA model to find the side wall tensions and bending moments. My question to the group is if anyone has done this before on similar silos and did it work out? The analysis will be pretty involved and I don’t want to waste the clients’ money if there is no chance this will work. Reinforcing the silo is not an option.
The silo walls are 10” thick with rings of reinforcing on both faces. So it has some bending moment capacity.
I can’t find a simple equation in silo design references to address this issue so my plan is to make an FEA model to find the side wall tensions and bending moments. My question to the group is if anyone has done this before on similar silos and did it work out? The analysis will be pretty involved and I don’t want to waste the clients’ money if there is no chance this will work. Reinforcing the silo is not an option.
The silo walls are 10” thick with rings of reinforcing on both faces. So it has some bending moment capacity.






RE: Offset Loading of Silo
RE: Offset Loading of Silo
The stone ladder is just a vertical series of boxes or ledges so when stone is dropped in the silo it doesn't fall straight to the bottom.
RE: Offset Loading of Silo
Be aware that, unlike a liquid storage tank, there are large variations in the design assumptions used for loading silos, and you may find that the original design seems very conservative or very unconservative on this basis alone. IE, if you do a FEM analysis of the existing silo as currently operating, there are no guarantees that design will check out, even without the change in loading.
RE: Offset Loading of Silo
RE: Offset Loading of Silo
For the bid, I went through and designed some large stiffeners to try to stabilize everything. And we were way high on the project.
A year or so later, I drove by and saw what the other contractor had done. No stiffeners. And there was a big ol' buckle up at the top of the silo. I guess nobody cared as long as it didn't fall down.
And, we've got a silo in a town up north of here with a big elephant's-foot bulge about halfway up.
So the moral, these things are NOT always adequate to begin with.