Special moment connection

[msquared48]

Anyone have any details they can post regarding making a moment connection between a 6X12 HSS shape (6" flat) bearing on the top of an 8" dia pipe column? This is for a pool roof structure for a residence. Only resisting vertical loads.

I have some ideas, but would like other opinions as this is a new one on me.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[slickdeals]

Can you provide a cap plate on the 8" pipe and then flare bevel weld the HSS to the cap plate?

 

[Ron]

Mike,
I would use a partial pen weld at the top of the column and fillet welded gussets off the HSS and down the column.

Another way is to weld a vertical plate, 10 inches wide and extending 6 inches below the bottom of the HSS. Slot the top of the column and set the plate in the slot. Use single bevel weld at the slots and fillet weld the top of column to HSS.

If you use a cap plate on the column, you will still likely need gussets, so no real reason for the cap (weld area at top of column to cap would control), assuming the wall thickness on the HSS is sufficient for all this.

 

[PMR06]

Since the 8" pipe is bigger than the beam, you could notch the top of column 12" deep x 6" wide to receive the beam. Then you'll have (4) 12" long vertical welds to develop the moment. Some half moon cap plates either side seal the whole thing up.

 

[Ron]

Mike,
Sorry....I read your post incorrectly...I was thinking you had the HSS on its side (brain fart).

PMR06 is right...notch the column...we do that a lot for aluminum structures. You have to check for tearing at the bottom of the notch. If you can extend the HSS through the column, you can add gussets on both sides. If not an aesthetic issue, I'd use gussets anyway, although you do have a lot of weld area.

If you haven't already done so, consider my first post the ramblings of a weekend idiot (I won't admit to full time idiocy just yet!)

Ron

 

[BAretired]

Why do you want a moment connection if you're resisting only vertical loads?

BA

 

[msquared48]

BA: To limit the deflection of the HSS as the price of steel is high, and the section I'm working with is on site.

Ron: I was thinking of using a cap plate with two kerfed stiffeners, one to either side of the HSS going down a foot or so at least into the column. Without the cap plate, I am concerned of overstressing the leading edge of the pipe column in local compression due to the leverage. I guess I will have to just run the numbers and check it out. Thanks all.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Mike,
I agree..compression failure of the pipe or the HSS wall just need to be checked.

I assumed that's why you were looking for a moment connection...I deal with it routinely in aluminum because my client has a set number of extruded sections and we have to sometimes play a variety of games to get them to work.

Ron

 

[connectegr]

I definitely use a cap plate. The HSS can be welded along the radius sides to the cap plate (BTC-P10), and along the edge of the plate to the HSS wall. I don't know why additional stiffening of the HSS would be needed. The load will be concentrated in the side walls, not the 6" face. The cap plate can be fillet welded to the 8" pipe, making the cap plate approx. 8 1/2" square.

You should be able to achieve the moment capacity of the column, but not the beam.

http://www.FerrellEngineering.com

 

[msquared48]

My guts tell me to use the top plate for bearing, but use a single kerf plate at the centerline of the pipe welded to the bottom of the top plate and extending a foot or so down the pipe to stiffen the pipe and bearing plate. I will try extending the top plate out 6" to 12" from the column, under the beam, and add two side plates on top (welded to the beam) to stiffen the extended plate. The kerf plate can be extended on a 45 to the underside of the extended plate.

Then weld the s@#$ out of everything. Probably an overkill, but it seems to flow. Push comes to shove, I can always add a knee brace. Options are good. Thanks to all.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[BAretired]

Mike,
You beat me to it with the side plates. See attached.

BA

 

[gtaw]

Top and bottom plates welded to the column and welded to the top and bottom of the rectangular HSS beam to develop the moment capacity of the HSS beam. Stiffeners to either side of the lower plate to develop the required shear and transfer bending loads to the pipe column.

Best regards - Al