Bridge Abutment Steel Cap

[sdock]

I am working on performing some design calcs on a steel abutment cap for a bridge. Where I work, a common type of abutment is constructed of a steel beam sat on top of steel h pile. The bottom flange of the cap is welded to the steel H pile. So essentially the steel cap is laterally supported on the bottom flange with only. I am confused on what to use for the unbraced length when performing lateral torsional buckling calcs.

 

[BridgeSmith]

How are the girders situated and attached to the cap?

Are there vertical stiffeners attached to the flanges above the piles?

 

[BridgeSmith]

Btw, this question should be in the Bridge Engineering subforum. You should see about getting it moved. Sorry, I'm not familiar with the workings of the site, so I'm not sure how to do that.