W Column to HSS Column Connection

[Heldbaum]

Guys, I would like to hear your opinion about the attached connection. This detail applies where column's section is changed from HSS 10x5x1/2 to W12x58..I believe EOR's intention was to create a moment frame above the floor where this detail applies that's why he changed the column size so drastically. All input much appreciated.
Thanks!

 

[KootK]

Perhaps you could share your thoughts and we could respond to those?

Assuming that you're right about the moment connection business, I'd offer the following:

- If the EOR is treating the bottom of the upper column as a pin joint, it looks fine to me.

- If the EOR is treating the bottom of the upper column as a fixed joint and trying to share moment with the beams, I'd call that questionable.

- Not sure I see the point of the seat angle either way.

- Not sure I see the point of the knife plate passing through unless we're moving axial load through the beams that can't be handled with the upper column bae plate.

What does the EOR have to say about it? Presently, we're all trying to read his or her mind.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BAretired]

It might be easier to move the cap plate to the underside of beam, running the beam continuously over the HSS column. The beam could have sloping stiffeners aligning with the WF flange above and HSS wall below. The WF would need a base plate over the top flange of the beam.

BA

 

[dhengr]

Heldbaum:
If I didn’t understand what the EOR intended, and what all the loads were, I would be inclined to ask him/her rather than some strangers from out in the either. I think you are going to have trouble getting at the 4 col. base pl. bolts with all that is going on around them, same goes for the beam bolts. I would not tie to col. base pl. from above to the beams below (plus the col. cap pl. below) the way that detail does. I would get rid of the 4 - 11/16" thk. beam stiffeners, I would lower the knife pl. about an inch, and I would cope the tops of the two beams. If you have seat angles, do you really need 3 - 7/8" bolts in the beam ends? Then, I would put a heavier cap pl. on the 10x5-1/2" HSS col. to essentially match the size of the base pl. above. I want to get the upper col. compression flg. load down into the HSS wall as directly as possible, if there is a significant moment at that connection.

 

[Heldbaum]

KootK ,dhengr,BAretired

Thanks for your opinion - I am going to talk with EOR undoubtedly. I posted it here just to get your general opinion, what your gut feeling is about the connection in general.

 

[dik]

Can you run the W beam over the column and splice at L/7 and frame the new column over the W beam? Add two stiffeners to match the HSS sides.

Dik

 

[Jerehmy]

I may be looking at this wrong, but I don't like the two bolts at the top flange of the beams. These bolts are going to attempt to restrain beam rotation at the column. I don't believe the two bolts will be strong enough to do this and there will be excessive deformation at the bolt holes or possibly failure of the bolts in shear.

 

[KootK]

These bolts are going to attempt to restrain beam rotation at the column.

That's an excellent point. Also, if those bolts are designed to transfer brace frame shear, it's unlikely that they'll provide enough slip to alleviate this concern.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bhiggins]

Wouldn't just be easier to terminate the HSS column below the beam line? That way you have a typical W-F to W-F connection.

Here's my attempt at the connection:

 

[haynewp]

My initial thoughts were:
1. Beam top flange restraint is created.
2. I don’t like the idea of any deformation potential of the HSS walls directly beneath a mismatched column above in terms of axial load transfer.
3. Incidental axial, shear, and moment from the above column can go at least partially through the lower beam’s shear connections.
4. The stiffeners probably aren’t doing much where they are located for axial downward loads from the above column if that is the intent.
5. I assume there is a floor diaphragm that is not shown bracing this connection out of plane.

Detail above by bhiggins looks a lot better.