Calculate Shear forces on a bolt midspan 1

[ochy38]

Im working on a beam problem that has my head spinning. It is an 8' beam with a splice 2' in along the span. The outer beam is a square aluminum tube and the inner sleeve is a solid piece of aluminum. I am trying to figure out the capacities of the bolts, the holes in the sleeve, and the holes in the beam.

Figuring out the stress due to bending at a certain spot along the tube or sleeve is easy enough, σ=My/I. That leaves me with a PSI unit. It's easy enough to convert that to a shear value for the bolt with its area.

Originally, the bolts were horizontal. I was able to easily calculate the stress using the above equation, at the farthest edge of the bolt from centroid, and taking the cross sectional area of material of either the tube or sleeve to determine a shear capacity of that part.

Now, with the bolts vertical, I am somewhat confused on how to find the capacities. It doesnt seem as straight forward as "max stress is this" and "stress acts on this cross sectional area", as the stress isnt a specific value. And what area would it actually act upon?

Appreciate any thoughts! I am aways removed from college and haven't done a problem like this in some time.

 

[jhnblgr]

What is the load?
How is this shape important to the design and impact it has on its function?
This isn’t exactly a tube and it seems likely the bolt into the shape would yield prior to the connection.

In theory the plate connection would be easy but the beam I would look at the stress distribution of the washer. I would ditch the outside sleeve idea that introduces too many issues with tolerances. You could place a sleeve on the inside likely with less issue heat the beam up and cool the sleeve down.

 

[ochy38]

jhnblgr - The shape I've posted is acting as a beam. I've designed what I've referred to as a sleeve, which is effectively a solid piece of aluminum that fills the entire interior cavity.

Yes - bolt bearing capacity of the holes is what controls here.

I began this thread asking how this sleeve might be designed as a moment transfer sleeve because my first iteration did not have enough capacity at the bolts to resist shear on the bolts caused by the moment of the beam. But with some other design changes and realizing I was applying an equation in the ADM incorrectly; I do have enough capacity at the bolts to resist the shear caused by moment lever.

Currently, I am trying to check if the bearing reaction of the "ends" of the sleeves will rupture thru the t-slot beam (due to bending moment of the beam).

I was able to come up with a point load at the end of the sleeve by using smoulder's step #3-

Im currently hung up on how exactly that shear force compares to capacity. Which I am wondering if shear capacity in this case would reasonably be calculated using the bottom half of the entire cross sectional area, because the bottom half is what would see the downward force.

I suppose if this was a w-beam, the web thickness X beam height would be the area used to determine shear capacity.

 

[rb1957]

Your fasteners have shear allowable (loads) ... don't they ? (mine do)
If not the shear allowable load would be Ftu*A ... or the applied shear stress P/A.
and *2 if in double shear.
And then check bearing.

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.