Column pinned connection 2

[Robbiee]

The attached sketch is a design of a pinned connection that I just did to carry a max. factored axial load of 646kN (145kips). The 2” pin is joining one top plate and two bottom plates. My questions:
1. Are there pre-manufactured connections similar to this one,
2. Would it be OK to have the bottom plates separated by more than the thickness of the top pate? In which case, the pin will be in bending and shear. I know that I have to resize to suit the span?
Any other comments are welcomed.
Thank you very much.

 

[JAE]

I don't think there are pre-manufactured connections like this. There may be, but I'm not sure I've seen them advertised.

Usually, I'd provide a slight gap between the plates simply to allow for installation tolerance and more free rotation.

Does this column rotate? If so how much? If it rotatates too far you could develop tensile uplift in the anchor bolts.

 

[civilperson]

Plate call out for bottom of column seems wrong,(20" circle x 1" thick is what I assume is needed). What size hole is used for the 2" pin? More than 46.2 ksi in bearing on the single plate, what type of steel or inserted bearing is proposed?

 

[Robbiee]

The hole should allow easy installation. Probably 0.02in clearance? The minimum specified tensile strength,(Fu), required for the plates and the pin is 65ksi.

 

[civilperson]

The pin and the single plate will both yield at bearing using the steel you specify. (145 kips on 2.0 square inches of area). Fu of 65 ksi is usually Fy of 50 ksi and the shear stress on the pin will be 145 kips divided by 6.28 sq in of steel, (double plane).

 

[Robbiee]

Civilperson,

I considered this a bolted connection, in which case bearing resistance is a function of Fu. But, I can increasing the plate thickness to 1-1/4".
Thanks

 

[gwynn]

AREMA specs deal specifically with pinned connections, as they have been commonly use on rail bridges. If I remember correctly they call for an allowable stress of 0.375Fy (I haven't seen this situation explicitly dealt with in an LSD design code unfortuneately). The low stress is to prevent yielding of the pin and plates, as Civilperson noted, since once any of the interfaces yield you no longer have a true pinned connection.

 

[hokie66]

Your detail only shows two plates, not three. There should be some hidden lines to indicate which one is inside. And I don't think the end plate is 1/8" round. Sorry to be picky, but poor drafting drives me to distraction.

 

[Robbiee]

Thanks all. All comments were well received and appreciated.

 

[abusementpark]

Why are you are so concerned about this connection being a true pin? Is there something present here where a standard base plate connection won't work??

 

[Robbiee]

The architect thinks it is an architectural feature.