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Unusual seated beam connection
2

Unusual seated beam connection

Unusual seated beam connection

(OP)
Due to unusual geometry constraints I'm unable to connect a new catwalk beam easily into the side of an existing steel floor beam. I'm planning on using a small angle as shown in the attached PDF. Loads are light (around 2 kips). Anyone done anything like this before?

Maine Professional and Structural Engineer. www.fepc.us
(Just passed the 16-hour SE exam, woohoo!)

RE: Unusual seated beam connection

I haven't done anything like that before, I would make them weld an outrigger plate and do an extended shear connection; it would only require welding on one side. I think that will be okay as long as the weld engages 1/2 the T dimension of the W8x15.

RE: Unusual seated beam connection

(OP)
Heavily trying to avoid welding to the existing steel due to poor weldability steel in the existing beam.

Maine Professional and Structural Engineer. www.fepc.us
(Just passed the 16-hour SE exam, woohoo!)

RE: Unusual seated beam connection

I've seen something similar for stair stringers.

RE: Unusual seated beam connection

2
TehMightyEngineer:
Cope the new W8 beam to fit over and past the web of the existing beam. Put a bot. flg. on the new beam, at the same elev. that you show the horiz. leg of your angle. Slot the bot. flg. pl. so that it goes 10-12" past a generous radius on the web cope (that is, on toward the center of the new beam), and can be welded to the web over the bearing seat and 10-12" into the new beam web. The problem with your detail is that you have a very high ripping force (tension) on the fillet welds at their terminations on the new beam web. And, these terminations are precarious stress locations to begin with, so don’t make them worse with that tension component.

RE: Unusual seated beam connection

(OP)
I like your thinking dhengr, that should work nicely and makes sense. I knew there was something nagging me in the back of my head and couldn't quite figure out what it was. Probably overkill for a 2 kip reaction but, being an industrial facility, I wouldn't be surprised if 15 years down the road someone tries to hang a few more tons off of the catwalk steel.

Maine Professional and Structural Engineer. www.fepc.us
(Just passed the 16-hour SE exam, woohoo!)

RE: Unusual seated beam connection

Your detail can be made palatable by:

1) Adding a vertical stiffener inside the angle and;
2) Designing the welds for the induced eccentricity.

For small loads, it's an economical approach.

Another version of Dhengr's detail uses one or two small angles instead of the slotted plate. Quite similar to a joist seat.

For loads as small as yours, you could also cantilever a pair of small angles from the square cut beam, avoiding the coping.

For all of the options mentioned above, you'll also need to convince yourself that you've provided adequate lateral restraint to the end of the beam. If you're engaging 4" if an 8" beam, you're probably fine. When I've been concerned about this, I've used an end plate in combination with the clip angle and stiffener.

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.

RE: Unusual seated beam connection

(OP)
Good points KootK. Torsional restraint is provided elsewhere on the beam. This end connection is simply for the vertical reaction and to avoid a bouncy floor where it transitions from my new catwalk to the existing wood floor. I might have them just weld something up for torsional restraint and if the weld holds then fine, if not then it's still fine.

Yes, after I made that attached image I thought that a stiffener might be required unless the angle could take the eccentricity in bending (though a stiffener is easy enough).

Two angles is a good idea, they need to build this quickly so the less complicated fabrication the better.

Maine Professional and Structural Engineer. www.fepc.us
(Just passed the 16-hour SE exam, woohoo!)

RE: Unusual seated beam connection

While the stiffener could certainly be used to help angle leg bending, that wasn't my intent with it. Rather, the stiffener seves to make the eccentric weld stresses predictable (linearly varying). It's meant to address the concern that Dhengr raised. But yeah, the cantilevered angles go fast too and can easily be made to extend to the girder web.

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.

RE: Unusual seated beam connection

(OP)
Weld came out to minimum fillet weld size controlled. Dumped my connection into Solidoworks FEA for shits and giggles, attached von mises results if you're curious. Shows that high ripping stress on the weld termination as expected. Stresses are low enough for me that I'm not worried about this ripping apart. This end of the catwalk has some redundancy in the supports as well so it's not going to take out the whole catwalk if someone screws up the welding either.

Maine Professional and Structural Engineer. www.fepc.us
(Just passed the 16-hour SE exam, woohoo!)

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