Diagonal Stiffeners in Special Moment Resisting Frames
Diagonal Stiffeners in Special Moment Resisting Frames
(OP)
I have been designing OMRF's for years and I have always used diagonal stiffeners in the panel zone when needed if the shear was to high. Now my office is starting to get into SMRF's and so I am reading FEMA 350 to learn how to design them properly. I can't help but notice that FEMA 350 requires doubler plates when the shear in the panel zone is too high. So I am wondering why FEMA 350 makes no mention of diagonal stiffeners as an alternative? Wouldn't they be just as effective as doubler plates? It just seems odd to me because in my office we pretty much use diagonal stiffeners 99% of the time just for the hell of it even if they aren't needed. Perhaps it has something to do with the way it affects the ductility of the SMRF. I guess the main question that I want answered is whether or not I am now forced to switch to doubler plates, or if it is still acceptable to stick with diagonal stiffeners. Thanks to anybody who can provide any insight on this issue.






RE: Diagonal Stiffeners in Special Moment Resisting Frames
With that said, if it's possible, it's my understanding that the doubler plates are very expensive to install. Therefore, if you can increase the weight of the column 30-40# a foot and avoid the doubler plate I've heard it's cheaper to do it that way. But maybe I'm wrong on that...
RE: Diagonal Stiffeners in Special Moment Resisting Frames
RE: Diagonal Stiffeners in Special Moment Resisting Frames
The behavior of a panel zone with a doubler plate seems to me to be very similar the behavior of a column with a thicker web.
But, the behavior of a moment connection with a diagonal stiffener does not seem all that similar in that you could get significantly different behavior for moment reversal (stiffener in compression vs tension).
RE: Diagonal Stiffeners in Special Moment Resisting Frames