HSS CRUSHING FORCE? 1

[Darken99]

I have a hss foundation which will be on located on the ground. I need to find the force which will crush the hss. There will not be a moment on the piece I just need to prevent the vertical walls of the foundation from bursting outwards under design conditions.

Thanks

 

[UcfSE]

Have you checked the walls of the HSS as little columns under compressive loads? Be conservative.

 

[Darken99]

Costwise it is cheaper to have a larger tube on its edge. Anyone else have any ideas how to calculate this?

 

[aggman]

I think UcfSE is giving you good advice. You should have an effective width that your load is applied over. This is more or less a web crippling problem which you can find an example in AISC 9th Ed ASD or by analyzing as an edge loaded plate. More simply you can check the wall as a column assuming end conditions and check it against buckling.

 

[JAE]

I'd agree...just use each wall as a finite mini-column supporting a load.

Say your tube supported a baseplate 12" x 12" so the load is assumed spread over at least a 12" long piece of tube. You could assume that it spreads out a bit beyond the 12" by d" where d is the tube height....

But then model the tube vertical walls as columns with height = d and fixed top and bottom against rotation but not against sidesway (k = 1.2).

 

[Darken99]

ok I will give that a shot

 

[mrMikee]

The above discusion makes sense, but I wonder what effect the radius on the tube corners will have on these calculations. This would cause a little eccentricty of the vertical load resulting in some bending.

Just asking however, I haven't thought this one through yet.

-Mike

 

[JAE]

You could model it in a good 2D program with the radius in there and the load applied to the flat section. But other than that, I don't know what else you could do short of testing some tubes in a lab. I think mrMikee has a good point.

 

[Darken99]

Does anyone know if the Ansys software in Inventor 10 can analize this type of stress?

 

[mrMikee]

Darken99,

AutoCAD Mechanical (not Mechanical Desktop) has a 2D FEA capability that I think would probably even be adequate to do what JAE suggests. I'm not familiar with how ANSYS works with Inventor but I assume it would be far more advanced. Some of the Inventor packages do include AutoCAD and AutoCAD Mechanical too.

-Mike

 

[trainguy]

The ANSYS software in inventor 10 is extremely basic. I believe this is a selling tool more than anything. For real FEA, I would not use it. I have done 1 analysis with it and was very wary of the results, based on the mesh geometry, comparison with manual calcs, and comparison with an Abaqus result produced by a friend of mine.

tg