Beam Connection to OWSJ (Open Web Steel Joist)

[BSVBD]

Please see attached Detail “A” & “B”…

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1484702735/tips/Connection_011717_dkmuzx.pdf[/url]

Through a previous discussion, I decided not to use Detail “A”.

Detail “B” is my next thought. I see I should consider mitering the angle corners, top & bottom, at the joist chords radii.

Any comments, concerns, cautions, other suggestions?

Thank you!

 

[KootK]

1) how much load are we dealing with here?

2) is the OWSJ new or existing?

3) if the OWSJ webbing suits this, it's kinda awesome mechanically.

4) Could probably do it with a double angle connection too, instead of the singe plate, if you wanted.

5) You're inducing a little torsion in the joist. Some bracing to the bottom chord might suit.

6) don't necessarily write off the other detail based on my comments in the other thread. I do it all the time for modest loads. I just try to grab both top chord angles.


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.

 

[Deker]

I have used the attached detail in the past.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1484704166/tips/joist_detail_azxqg0.pdf[/url]

 

[jike]

Obviously, Detail A is for light loads and Detail B is for heavier loads. Make sure that you accurately know the dimensions between supports and the width of the supports for Detail A as the gap will control the thickness of the support angle. I have seen some field problems with this detail although it is very commonly used.

 

[BSVBD]

Koot...

1) 6K

2) All new construction. I would provide the detail and load diagram to the OWSJ supplier and thus specify an "SP" (special) joist.

3) The joist supplier / manufacturer should design the joist to accommodate the/this detail I provide on the bid and construction documents.

4) I will consider the double angle. Do you mean inserting the beam web between the angles? Likely more difficult erection; the same detail will be used each end of beam. This beam supports a maintenance stair leading up to a penthouse.

5) I can work that out with the joist supplier.

6) I've done the Detail "A" before also, but, it was to support the back-span of a cantilever resulting in near "0" axial or uplift reaction. That case was easy.

a. When i so a simple fixed end, "cantilever" analysis of the outstanding angle leg, I'm amazed at how weak the leg is in the analysis. Maybe I'm doing something wrong.​

Thank you, always, for your input!

Deker... Good suggestion! I will consider it.

jike... fortunately, i've got a wonderful (20-year) relationship with a competent general contractor. Although field problems are inevitable, we typically solve them together in a reasonable manner.

Any other suggestions are welcome.

Thank you all!

 

[KootK]

With the double angle suggestion, I meant a connection exactly like we'd use in a normal beam to girder commection. The outstanding flanges of the double angles would bolt to the outstanding flanges of the angles in the OWSJ. The beam web would indeed be sandwiched but the angles would ship loose so erection shouldn't be a problem. Especially since I'd provide slotted holes for fitup in both directions.

If I were the joist supplier. I'd want a connection that delivered the load straight to the webs on both sides of the truss. That way, you wouldn't have to move 3K across the chord. No doubt we can leave that to the joist designer.

A wide flange would definitely have some advantages here. Not sure how the economics shake out.



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.