Steel Beam Connection / high snow & eccentric connection 2

[BTStructural]

Soooo, a contractor forgot to install a supporting steel column in a residential construction project, the home is all framed up with roof on, and the supporting steel column cannot now be installed directly below the steel beam as they misplaced the steel beam's location and it falls near the end of a garage door whose operation would not work anymore if we put the column directly below the beam. Quite the pickle.

This is in a high snow region. Using 1.2D + 1.6S I'm designing for a reaction of 44kips. I'm thinking that the best way to pick up the load is with a welded shear tab to a beam stiffener, allowing me to pick up the load very near the center of the beam (see detail).

From what I've seen the welded shear tab connection isn't specifically approved outside of a moment connection but is widely used in retrofit situations. Studies seem to have shown that the rigidity of the shear tab connection is more influenced by other factors than welds vs bolts anyways, such as thickness of the plate. However, the plate is a bit longer than the typical conventional condition for shear tabs I believe, and so I'm considering using the column cap over the shear tab to stiffen the connection. I guess that is one dilemma - stiffen the connection here due to the extended shear tab or not stiffen so as to allow rotation of the shear tab and help keep it a pinned connection. I feel like the weld handshake going on here will almost create a regular shear tab connection already (as opposed to the more extended shear tab scenario) but I plan on tying the top of the column into the floor's wood diaphragm regardless.

Anyways, thoughts on this connection would be appreciated. I may be able to weld a smaller WT section at the bottom to act as a seat, not sure that would really do much though (?) and space is limited to allow the garage door to still function.

On the plus side, the home made it through the winter without issue so maybe none of this is critical in the end but I designed it a certain way and I'd like to have the column in with a proper connection

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1682134244/tips/r1_n2ske7.pdf[/url]

 

[dik]

As long as your column can be braced, laterally, there should be little issue in designing the column for a point load of 44K and an eccentricity of about 8", including any P-delta effects. The column, hopefully isn't too high. Shear loads don't appear to be too high, and the rest is just design.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SWComposites]

Suggest using two shear tabs on either side of the column, with the shear tabs overlapping the column sides and welded all around. This looks like something that should be really stout and has allowance for imperfect welding. And use the cap on top of the shear tabs.

 

[BTStructural]

Thank you both!

@dik, the column is only about 9' tall (inside a typical residential garage).

 

[dhengr]

BTStructural:
SWComposites has the right idea, you don’t want to put that reaction load into the column in the middle of the left side face, which would cause a very high out-of-plane bending/punching situation in that col. face. The two side (shear tab type) plates, one each side of the column are much better. Fit them into the beam btwn. the two flanges and into the beam web. The web stiffener pls. really serve no purpose in this detail, and could be left off. Furthermore, the welds you show btwn. the web stiffener and your shear tab can’t really be made because of the poor access to those welds, given their psoitions. The two side pls. should run from the top of the top flg. on the beam (with a cope) to the top of the bot. flg. and from the web (with clipped corners) to within about 2" of the right side of th col. This gives you some adjustability w.r.t. the beam and col. locations. The cap pl. should be about 7.5 or 8" wide so it can be welded to the col., to your side pls. and to the top of the beam. Then, the grout under the col. base can adjust in height/thickness for vert. adjustment.

 

[dik]

Not likely stability issues, but check as a beam-column anyway. Good idea about eccentric loading on the clip, but can be designed to accommodate this.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JLNJ]

It's not a shear tab, it's a moment connection to the face of an HSS shape. 30'-k of load transfer plus 44k of shear is no joke. You need to develop almost the full section of the HSS6x6. You might need to consider an interior web plate inside the column. Or maybe some stout plates on both sides. You also have about 2500# of thrust to resolve.