Roof Lacing Angles

[juneng]

Hello All,
My question is in regards to 'lacing angles' often found at the top flange of exterior roof members of steel framed building when used in a stud framed wall application. Is this a common practice? Where can I find further information on this application/detail?
My engineering sense tells me that this application eliminates the need for the examination of the weak axis bending of the exterior beam where the stud framing would attach to the top flange through the perimeter angle. This would create a uniform distribution of the wind loads to the steel roof diaphragm.
I understand time is money in the engineering world- but could anyone tell me if this is good practice or a wasteful use of steel?
Thanks,
JE

 

[DaveAtkins]

There are two situations where I use lacing angles:
1. No roof diaphragm available (e.g., standing seam roof).
2. The exterior walls are framed with horizontal girts which span to "wind" columns. The reaction at each wind column must be resisted by lacing angles which put the load into the roof diaphragm.

DaveAtkins