Vulcraft Long Span Joist - Axial Load

[cgstrucg]

Hello,

I am working on a project in NYC which has a lot of roof long-span joists. As per vulcraft, we need to provide them a load table for each special/simple joist. I am creating that load table for vulcarft and I am stuck at one point. They mention in the table to specify axial loads for both joist girders and simple span joists.

My question is - Do they mean axial loads at the joist end (joist seats) because of seismic/wind? I am asking this because the axial load might vary along the full length of the chord and that will get really hard to check. See attached for table snapshot.

Thanks

 

[KootK]

1) I think they'd be wanting axial loads that are externally applied to the chords and not axial loads arising from flexure.

2) For drag elements, I suppose that you could have varying axial. That said, I strongly suspect that they'd design the joists for the highest value treated as though it were applied at the ends. And I'd specify it that way.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[msquared48]

Possibly from drag forces or expansion/contraction.

Call and ask Vulcraft...

Mike McCann, PE, SE (WA, HI)

 

[Corndwg01]

They're looking for wind/seismic axials. If you have high axials, don't forget to supply a method of transfer, such as tie plates, so they don't have to go through the joist seats.

 

[cgstrucg]

That's what I thought. Axial because of wind and seismic at joist seats. Thanks everyone.