Silo loading on Structural Analysis Software

[iffranco]

Hello. I'm currently studying granular material silo analysis and design. Up to now, I know how to calculate the horizontal and vertical pressures the stored material exerts on the silo walls via Janssen's Method. I want to analyse the silo with a structural analysis software like SAP2000 or RSAP, but it is not yet clear to me how should I load the finite elements.

For horizontal pressure, it is similar to hydrostatic pressure on the walls. But for vertical pressure, I'm not sure how to apply the pressures on the finite elements. One way I thought it could be done is by applying a linearly distributed load on the perimeter of the sections that make up the silo, but I'm not sure if it is theorethically correct.

Can someone help me to clarify my doubts?

Regards

Ivan Franco

 

[FlashSet]

Why is there a vertical pressure on your elements? Is your silo cylindrical? conical? upside-down conical? Are you referring to frictional down drag? Are you referring to the the vertical pressure from the granular material inside the silo?

If you clarify these questions I may be able to better help you.

 

[jhardy1]

You should apply a "Traction Load" (may be called a "Face Shear Stress" or similar in your software) acting vertically downwards onto the wall elements which are loaded by the stored material to represent the down-the-wall friction load.

http://julianh72.blogspot.com

 

[gyung]

Setup a custom polar coordination system (R and Phi) at the centre base of silo could be a handy way to apply wall pressure. The pressure can be applied as a function of silo height as well as angle (FEA program e.g. Strand7 allows user to input load in terms of x,y,z or r,phi,z).

You might want to consider wind load acting on the silo wall as part of the design if it is located outdoor. The wind load can be unevenly distributed on the silo parameter. Wall pressure applied as a function of polar angle is useful when considering wind action.

Hope my sharing useful.