sagrod configuration
sagrod configuration
(OP)
I'm looking at this monoslope roof sagrod configuration.
This is one of the goby drawings I have.
Does this type of sagrod configuration work?
This is one of the goby drawings I have.
Does this type of sagrod configuration work?






RE: sagrod configuration
RE: sagrod configuration
RE: sagrod configuration
RE: sagrod configuration
In many situations (standing seam), the roofing for a structure like this will not be a competent diaphragm and it is really the sag rods that keep a portion of the the gravity load of the roof from becoming weak axis bending the in the purlins. On a dual sloped roof, there will be connection between the sag rods on either side of the ridge so that none of the channels have to absorb the accumulated sag rod force as weak axis bending. With a mono slope roof, it's a different animal.
In the absence of a diaphragm, the down slope component of your gravity load will be:
1) loading your top most channel in weak axis bending if it is stiff enough to attract the load.
2) loading all of your channels in roughly equal week axis bending in which case the sag rod has little purpose unless it is intended for lateral torsional restraint.
I don't believe that it's normal practice to count on sag rods to restrain lateral torsional buckling in roof purlins. That said, it is a pretty normal practice to use them to restrain lateral torsional buckling in girts.
I don't love the angles. As shown, they would put the fillet welds to the channel webs in direct bending which is generally a no-no for welds. Perhaps it's acceptable in this instance with the loads being pretty minor.
This position statement by Canam may be of interested. Kind of sounds as though the official party line on this has been in flux. We've got a couple of PEMB industry experts on this forum. Hopefully one of them chimes in.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: sagrod configuration
RE: sagrod configuration
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: sagrod configuration
Dave
Thaidavid
RE: sagrod configuration
RE: sagrod configuration
RE: sagrod configuration
RE: sagrod configuration
Unless you're willing to utilize each channel in weak axis bending, I feel that you still need some kind of in plane roof diaphragm. Probably discrete bracing by the sound of it. I need to know more about the building in order to recommend an appropriate scheme. Plan dimensions, supporting framing scheme... stuff of that sort.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.