C-Shaped, Gap Plate, Line Weld

[LearningAlways]

I am rehashing weld details and this is something that I struggle to agree with.

For a gap plate that has a c-shape weld on one side and a line weld on the other, the assumption is that one side is fixed and the other is pinned. Thus the c-shaped side takes into account load eccentricity from the line weld but that is not true from the line load perspective.

I don't see how the line load doesn't resist rotation and therefore doesn't undergo additional stresses. Despite the assumptions, the physical behavior suggests that both sides resist the eccentric loading.

I've attached a snip. I've accepted that this is the assumption but I don't agree with it. Can someone help reconcile the behavior and the assumption?

 

[ProgrammingPE]

If you are transferring shear, V, some distance through a plate, e, you will have a moment of V*e. This can be resisted entirely by either end or some combination of the two as long as the total moment is supported. (Basically, the location of the hinge will be somewhere between the two ends.)

If the connection at one end is stiffer than the other, it is common to just treat the less stiff end as the hinge and design the stiffer end to resist the entire moment. In reality, some moment will be transferred at the less stiff end, but if it begins to be overstressed, it will become less stiff and transfer all of the moment to the stiffer end which matches the original design assumption.

There's a section in Part 10 of the Steel Construction Manual on "Shear Splices" which discusses this some.

What is this plate being attached to? I would think that the actual location of the hinge would also depend on the rotational stiffness of the supported and supporting members.

Structural Engineering Software:

http://www.structuralcentral.com

Structural Engineering Videos:

http://www.youtube.com/channel/UCOj2mXXf3ZbZtgxTc6BtkGg

 

[LearningAlways]

Thank you ProgrammingPE, that was a great clarification.

This plate is for a precast wall-to-foundation connection, so the rotational stiffness of the members is rather stiff. Seems I was looking strictly at the free-body diagram of the weld and couldn't see the forest for the trees.

And thank you for the code reference too!