Bottom flange cope to clear existing column 1

[n8engr]

I am working on a connection detail that I would like some input on. It involves new beams going over top of an existing column. The new beam sizes had to be increased to support larger loads, but the existing column will remain.

Since the new beams are deeper they won't go over top the column without having the section reduced at the column interface. (See attached sketch) The top of steel elevation cannot be raised due to constraints of existing steel elevations that have to be tied into.

What is the best way to transfer the forces through the beam into the reduced section? Have any of you had success with certain application versus others? Recommendations are appreciated...Thanks.

 

[Lion06]

The bottom plate of the reduced section should be extended into the web of the full section. The vertical plates at the reduced section will need to be broken into two pieces on each side of the web.

 

[tadeng]

Is there an existing cap plate on the column? If so, can the column be cut off just below the bottom of the new beams, and a new cap plate added? This would allow the beam to bear on the new cap plate.

 

[msquared48]

Check your web shearing stresses over the column. You might need a doubler if the section is reduced too much.

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

 

[hokie66]

Agree with SEIT and Mike as to the detail. Split the new bottom flange around the web, extend say 12". Check web shear.

 

[paddingtongreen]

In the detail suggested by StructuralEIT, remember that the force in that bottom plate has to get from that plate into the flange of the full section, via the web.

I tend to make the ends of the cut-out, sloped, and weld pieces of plate to the web, so as to be the flange following the shape of the web cut out. Then I put vertical stiffeners above the flange plate junctions.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Ron]

tadeng's idea should be considered. If that's not possible, then do as hokie66 and Mike noted.

 

[slickdeals]

How about removing the existing cap plate and adding a new W12 milled to bear and have bolted flange plates connecting the new and old W12. The W36 can then be a regular shear connection.

 

[hokie66]

slickdeals,
That involves too much site work. You can mill the new piece of W12, but not the existing. Then you have a lot of holes to drill on site. Best to stick with a solution that can be shop fabricated.

 

[ToadJones]

I have had occasion to design many seated-type connections like this.
As others have suggested, knife the seat plate around the web and extend it some distance lengthwise with the web. Essentially what you have is a WF shape to analyze for shear, web buckling etc.
Remember too, that stiffeners are a requirement at un-framed ends of beams...if these are un-framed.

I hope this isn't a crane runway!!!!

see generic sketch attached

 

[ToadJones]

helps to attach it, huh?