Bolts or rivets in bearing type connections with spacers

[trainguy]

Hi all.

Looking for guidance in appropriately sizing rivets (both well-clamped and not so well clamped) in bearing-type connections.

In lining up members in an axial splice, I am expecting some misalignment. Spacers will therefore be needed. The splice can be thought of as a long bolted joint in single shear, similar to a column flange splice but actually it's a side sill on a railcar. Is there a guideline on max thickness of spacers under which the bolt shear and bearing strength are still good, or is there a guideline with reduction factors, etc?

The member is in tension (12k) most of its in-service life, but in compression (90k) under the proof loading (train to train impact) case. I expect that in service the joint should work as a friction type connection, but in the proof load case, there is slip.

Any thoughts?

 

[racookpe1978]

Going to depend on several factors: It's easiest to exaggerate the two extreme (but realistic) cases so you can see the differences:

Very wide diameters, very thin base metals and spacers. Larger diameter rivet.
Thus, two 1-1/2 diameter washers x 1/8 thick around a 3/4 inch dia rivet clamping two 1/8 (or 1/4) plates = almost no twisting effect at all, even if the "slop" around the inside rivet is as much as 3/8 inch. Pure sliding, and the shear is resisted by either friction (from the clamp) or the "stop" point when the rivet hits the side of the hole.

Very tall spacers, small dia rivet and rivet head with modest clearances.
The joint acts like an axle = almost pure moment about the first base plate.

So start by defining your approximate sizes and clearances.

 

[dhengr]

Trainguy:
I sure would like to see some details of the side sill you are dealing with, and the car parts you are having to work around in dealing with the side sill. Why are there spacers, where are the spacers? Are these splices on flanges or webs, or both? Are the side sills the primary longitudinal members or is there a center sill, which is the primary longit. member? What kind of members are the side sills? Is this a repair or re-building job? I don’t think you can have it both ways, a slip critical joint for the 12k tension and then joint slippage and bearing during the 90k buff load. Or, the joint will likely loosen up. Are you using hot driven rivets which fill the holes when driving and then provide some clamping on cooling contraction. Or are you using huckbolts, or some such, which provide some clamping force but otherwise act more like bolts in an imperfect hole. Why not weld the spice pl. to the newer (replacement) member section, have the other half of the splice pl. pre-drilled, to a pretty tight fit with the bolt dia. Then, upon fit-up use the splice pl. holes as a drilling template for the holes in the existing member section. This should give you better bolt/bolt hole fit-up and matching.

 

[trainguy]

Guys,

I guess I didn't describe this well. The misalignment I expect is not hole to hole, it is with respect to the thickness of the connected plates. These are 5/8 thick, and may be offset by maybe 1/8 at the butt joint. The splice mechanism is a Huck bolted tie plate with ample fastening. Very likely, I'll need a shim, also often called a filler plate.

tg

 

[trainguy]

And some more info:

Side sill webs and flanges are 5/8 thick. This is a new aluminum extrusion that will be spliced to an existing one. Fillers will probably be required based on tolerancing and thicknesses not matching up, but we need the rivets to install tightly.

Rivets are 1/2 inch diameter Huck C50L. (Client wants BOMS, but those do not clamp well).

Side sill participates with center sill and side walls, with each side sill taking about 1/8 of total 800k buff load.

dh: We usually place pilot holes on one part and match drill out to slightly larger size at installation as you suggest.

tg

 

[trainguy]

Anyone?

 

[Kwan]

I would consider the shim as floating. This causes a moment on the fasteners so check for bending in the fasteners.
If too much bending, extend the shim and install fasteners in the shim to tie it to one side of the joint. (make it a structural shim).
Hope this helps.

 

[Lomarandil]

Kwan's approach seems reasonable.

Also AISCJ5.2 has some guidance on filler plates affecting the shear capacity of bolts. That may be useful, though I'm not familiar with huck bolts to know if they are technically covered in RCSC