Joist Girders as Perimeter Framing

[jorgen1212]

Are there any reasons why Joist Girders should not be used as perimeter framing members.
I've heard there are drag strut issues, related to the connnection between the perimeter steel deck and perimeter framing (exterior diaphragm fastening)
Also, has anyone used Joist Girders for concentrically braced frames.

 

[SteelPE]

My old business partner used to use joist girders in concentrically braced frames before we went into business. I can tell you that in 12+ years I don't think I have seen anyone do it though. Seems like a detail from the past. With all the seismic connection requirements it may be very difficult to do.

I have used JG in perimeter framing. You need to make sure you can drive the loads though the chords of the girders and from one girder to the next. You also need to make sure that you indicate the loads properly to the joist MFR.

 

[haynewp]

As drag struts should be fine if the deck welds can transfer the force, I have taken a lot of wind load through joists before as struts and just shown the loads on my drawings for the mfr. Also show the rollover forces in the joist seats where where they are sitting on the joist girders. Too much rollover force can be expensive to deal with and possibly can't be designed for without additional transfer members between the joists. Ask a joist mfr about accommodating the loads on your project.

I have never used a joist girder in a braced frame, I think the eccentricity of where the brace connects relative to the joist girder connection to the column would be problematic in a cross braced concentric frame. I wouldn't try a chevron brace on a joist girder. I suggest using a beam for either case.