Pile cap vertical welded plate unbraced length 1

[pile.driver95]

I'm designing a cap plate support for a driven steel pile. I've got a horizontal cap plate which supports a piece of equipment, supported by two vertical plates: one vertical plate welded to each flange of the steel pile. I'm looking to determine the thickness of the vertical plates under combined loading. I'm looking at this vertical plate as a beam-column, K = 2 (top plate is restrained against rotation), but trying to determine the unbraced length. I want the answer to be "distance from bottom of cap plate to top of vertical plate weld" but thinking it's more like "distance from bottom of cap plate to centroid of vertical plate weld". I've tried applying gusset/Whitmore logic here but having a hard time convincing myself that's useful. Welding at the bottom lip of the vertical plate is not possible.

Any ideas?


Thanks!

 

[KootK]

I'd be comfortable with:

- K = 2.0; each plate free at the top and cantilevered up from the pile.

- L = distance from top of weld group to underside of cap.

You'll get some rotational restraint at the top and that ought to offset any tendency for the lower restraint to be a bit lower than the top of the weld group.

 

[BridgeSmith]

Is there a reason the cap plate can't be directly attached to the pile? Driven piles have to be cut off after driving, anyway.