Silo Foundation

[francis_intano]

Good day!

Do you have a reference for a ballpark figure of support reactions from a 4-legged silo. I know I have to check for overturning due to wind when empty, aside from that I think I have to consider seismic effects too. Any reference in designing a foundation for a silo would actually help. Thanks a lot!

 

[rowingengineer]

You need the silo specs, the reaction can vary significantly.

 

[HTURKAK]

I will suggest you to look Pressure Vessel Design Handbook , Section 5 ( By Bednar )

and thread794-472011..

You may prefer to provide more info . to get better responds..

 

[human909]

I do this regularly. Things to be aware of:
-A ball park figure of combined leg loads are 1.5-2x the silo tonnage, so for a 4 legged silo you'd be looking at 0.4-0.5x of total silo storage tonnage
-For many hopper silos overturning due to wind dominates foundation design
-Generally a raft slab is ideal, for larger silos with more legs a ring or hollow octogen also works well. For large silos in poor soils, piles might be needed.
-Four legged silos generally have a critical load cases of wind/seismic at 45 degrees
-I would consider it prudent to consider FULL bulk storage live load when considering seismic loads

 

[JStephen]

Agreed with the above.
In the case of Bednar's approach, note that he assumes "short" unbraced legs, with the legs fixed against rotation at the base by the baseplates. If your silo is very low, this may work, but for many vessels, it won't, and of course for braced legs, things are different.
For the seismic, loading may be limited by yielding of certain elements, so loading will depend on actual construction details, not just on overall weight and mass distribution.