Box Girder Internal Bearing Stiffeners

[efFeb]

Good Afternoon,
I feel like after this week, I will owe everyone on engtips a coffee, but I have one more topic that I would love some input on.
I have columns (typ. col is W10x54) transferring onto box girders (typ. box girder 20" wide x 25" deep). I need to get this force into the webs of my box girder, so want to design a full-depth internal stiffener to accomplish this. I am thinking to select the plate thickness by checking the stiffener as a column, as is mentioned in S16-14 cl. 14.4.2. If anyone has any feedback on any considerations I might be missing here, I would love to hear this.
In addition, I am finding the width:thickness ratio in Table 1 for plate girder stiffeners to very dramatically govern the thickness of the plate required. Because I am planning to weld the internal plate at the top and two sides, is it necessary to use such a stringent requirement? This seems more suited to an element supported only on one side.
I've provided some sketches below of the condition I have, and what I am thinking to do:

Thank-you all so much again, I really love hearing your ideas and advice!

 

[r13]

What type of loads in the column? For gravity load alone, if the top plate of the box girder is stiff enough, I don't feel internal stiffener direct under column web is necessary. However, you should check stiffener requirement along the box girder, and provide externally, as per code provisions.

If plates of the box girder are quite flexible, I would suggest add a column baseplate, and all around stiffeners (plate or angle steel) on both side of the column.

 

[KootK]

First off, plate buckling is not my strong suit. Hopefully some of the bridge guys chime in.

Secondly, I agree, your calculated thickness does seem unreasonable and the situation surely is quite different from the one contemplated in the S16 clause.

Technically, I believe that this is a case of a plate under varying compression. All that follows is from Guide to Stability Design Criteria for Metal Structures.