CFS X-Bracing 5

[dik]

A colleague is looking for design information and details for cross-bracing steel stud bearing walls against lateral wind loads (no seismic). Detailed calculation would be handy. Can anyone assist or point me in the direction?

thanks, Dik

 

[Ron]

dik...are you asking about "in plane" cross bracing, perpendicular to the lateral loading? If so, I have typically trussed those when extra shear capacity was needed or where there were large openings.

 

[dik]

on the inside and/or outside face of the 2X8 CFS walls.

Dik

 

[Ron]

I have used plywood on either face. Typically 1/2" to 3/4" thickness. Prefer over OSB. If on exterior face, I use PT plywood in the lower 4 feet for moisture consideration.

 

[dik]

The wall and cladding has to be non-combustible.

Dik

 

[Ron]

Geez dik....you're making it more difficult! Use 14 gauge sheet metal strips (4" wide) placed diagonally..for calculations, only tension in the strips and fastener shear need to be considered. Well...check compression/buckling, but shouldn't be an issue with diagonal placement.

 

[Ron]

dik...the other option is to double the studs and screw them together....overkill, but works.

 

[SlideRuleEra]

Maybe this tech note, Design of Diagonal Strap Bracing Lateral Force Resisting Systems for the 2006 IBC, from the Cold-Formed Steel Engineers Institute, will complement the bracing Ron has suggested.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[dik]

Thanks Ron... the only other time I used strap cross-bracing was for the exterior wall of the Sears store at Polo Park. Contractor forgot the angle cross bracing and I got a panicked call on a Friday afternoon... steel stud and brick veneer (no access from the outside) with an opening date looming... first time I ever used strap and pop rivets.

Dik

 

[dik]

What sort of fastener is usually used for the vertical component at the base of the angled cross-bracing? Does anyone make a bolt that can be epoxied into a gradebeam/wall and with an attached plate that can be screwed to the stud? Haven't looked at the AISI publications from SRE, yet. I assume there are load tables for the various manufacturers on site. I'll spec a particular manufacturer or an app'd equal.

Dik

 

[Ron]

Tapcons should be sufficient if you want to fasten to concrete. Usually only fastened to studs and track.

 

[dik]

tapcons, I like... thanks

Dik

 

[structSU10]

We typically use hold down similar to wood shear walls. the steel network has some info, as well as simpson.

 

[XR250]

What sort of fastener is usually used for the vertical component at the base of the angled cross-bracing?

I used to use a section of MC6x18 embedded in the track and epoxy anchored into the fdn. The strap was welded to the vertical leg.
At the top, I showed a heavy gage deep leg track for the length of the shearwall. The strap was then welded of screwed to it.

 

[dik]

Thanks, gentlemen.

SSU: I've used Simpson products for wood; will take a look. I'll try to find out what the magnitude of the forces are.

Dik

 

[bhiggins]

Here are some nice details I've found.

 

[dik]

bhiggins: Thanks very much.

Dik