Shear Pin

[engpes]

I am designing a double shear pin connection that does experience some moment. The connection consists of a 5x5x3/8 tubing fitting outside a 4x4x3/8 tubing with a 1" pin passing through both.

The clearance between these members is approximately 1/4". This leads to some moments that will be generated.

I have checked (ASD) the pin for both allowable shear stresses (0.4*Sy) and allowable moments (0.6*Sy). My question is this:

1.) Is there an AISC unity check that deals with shear and moment in pin connector? Am I adequate with just check the allowable shears and moments independently?


I know these stresses happen at different locations in the cross section, but I cant find any unity check that deals with this. Thanks a lot.

 

[ToadJones]

Be aware that Pins are designed differently than Bolts.

 

[engpes]

Am I correct that I can check the shear stress and bending stresses separately?

Thanks,

 

[ToadJones]

Generally speaking, the interaction equations of AISC do not include shear. Biaxial bending and axial.
Tension
Shear
Combined Tension and Shear

Maybe you could use some shims or something to help eliminate bending.

 

[a2mfk]

Can you weld a plate to the inside member to act as a shim to close the 1/4" gap?

I also would not lose much sleep over ignoring that 1/4" gap, I may just add some additional capacity to the pin/bolt.

 

[SAIL3]

This may not answer your question directly.
I had a somewhat similar problem recently.
Two round pipes, one inside the other similar to your problem but with a gap between the two of less than the 1/4" that you are dealing with..it was more like a slip fit.
What I found out was that if there is no axial load in the members, then this conn has the capacity to resist a moment without any shear pin.
In fact, the deflection due to bending causes the outer pipe to oval in Y-direction while the inner pipe tries to oval in X-direction, one stabilizing the other. The weak link is in the smaller pipe, right at the edge of the conn.
Shear is developed between the inner and outer pipes thru friction and if the two pipes are prevented from moving apart the connection "as is" is stronger than the larger pipe provided that there is enough overlap of the two pipes.

 

[SAIL3]

Sorry, should have added comment on your situation directly.
Is there bending in your pin? Probably,with the 1/4" gap, but could be difficult to quantify.
Since, stability is not an issue here with the pin, then checking for moment and shear independently is one check.
I would also check the resultant stress from the bending and shear.
I would also overdesign it because of the uncertainty of the magnitude of any moment in the pin due to local deflection of the tubes.

 

[ToadJones]

also, generally speaking, connection elements are not checked for combined stresses.
See the bottom of page 9-3 of AISC 360-05 manual.

 

[SAIL3]

Forgot to mention that I would also design the ends of the members for any applical design paramaters used in lift lug design.