Tie force method for metal roof deck

[lctq]

Under the new UFC 4-023-03 (July 2009), there is a rotation requirement of .20 radians for the members acting as ties in the floors and roof (tie force method). This seems to force us to use rebars for ties in the floors. What about the roof? Does this mean we have to have concrete on the roof? Does anyone have any experience with this?

 

[steellion]

My understanding is adding concrete and rebar to the roof is definitely the easiest way to meet tie force requirements, but not the only way. I went to a Prog. Collapse seminar recently and spoke with an engineer from another company that was able to meet tie forces using open-web joists and some sort of special detailing beyond that.

Project factors such as area of roof, type of contract, and schedule will factor in as to what your best solution will be.