W-shape roof beam uplift bracing

[bsh117]

Hello all!

I have a single story building with bar joists bearing on steel beams. In this particular case I have a 31'-6" span and the loading on that beam is DL=.687 klf, LL=.687 klf, Ult WL uplift=-.721 klf. In order to reduce the size of the roof beam, I've decided to brace the bottom flange of the beam with angles kicking up to the first panel point of the joist top chords. Can you guys give me some input on what reaction I'll need to show for the joist engineer at this brace point? Would it be 2% of the compression flange force or would it be the trib area of the uplift force? Thanks!

 

[KootK]

It would be the 2% brace force or, better yet in the US, the force calculated from the AISC SCM appendix that covers bracing requirements. I would expect that the OWSJ engineer will deal with the vertical component of that force with you dealing with moving the horizontal component into the roof deck.

 

[bsh117]

Thanks @Kootk!

 

[KootK]

Happy to help bsh114.