Horizontal Bracing

[strguy11]

I have an existing building in a high seismic area, that we are renovation. In order to get the metal roof decking to withstand the shear loads, I calculate that 18 ga deck with (11) welds along the sidelaps (1500 plf capacity). I doubt however the existing roof deck is this guage.

Has anyone ever used horizontal braces? I was thinking of attaching angles or other sections to the bottom chord of the joists, since it may be difficult to run through the webs. Are there any good design guides for this? I assume the design would be just simple T or C members, right?

 

[dik]

Can you use sheet material such as 18 GA X 12"(?) wide and pop rivet it to the existing deck?

I had a project about 25 years ago that the X-bracing was missed by the fabricator and the construction review caught it. The wall was brick veneer on steel stud and the stud and brick work had been installed... used sheet material with pop rivets to replace the metal angle bracing. First time I ever used pop rivets for a structural application.

Dik

 

[strguy11]

The owner and architect want to reuse the roofing material, so no I cant.

 

[dik]

Can it be fit in from undertneath... with the bracing problem, the sheet material was chosen because it fit on the outside face of the steel stud and the exterior grade drywall was lifted locally to accommodate it.

Dik

 

[jike]

You may also have to reinforce the joist bottom chords which act as compression struts and possibly the chords of the horizontal trusses.