eave struts
eave struts
(OP)
Hello all;
I am currently designing a single story steel framed building for an industrial application (W sections for columns and roof beams, cold formed channels for girts, and channels for purlins (roof heights have limited me to small C4's for purlins instead of using the traditional cold formed channels (CFC) that would have required me to use for example 8" CFC). The building is braced therefore not a portal frame and it is a single sloped roof at 1:12 pitch.
My question now is how can I detail the eave and gable ends of the roof without using an eave strut (i.e. a deformed channel for the lack of a better description "cantilevered" off the column). Is there a way I can use traditional members? My wall girts are 8" CFC that are mounted to the outside face of the columns (again I did this to increase the amount of space inside the building).
Thanks,
M.
I am currently designing a single story steel framed building for an industrial application (W sections for columns and roof beams, cold formed channels for girts, and channels for purlins (roof heights have limited me to small C4's for purlins instead of using the traditional cold formed channels (CFC) that would have required me to use for example 8" CFC). The building is braced therefore not a portal frame and it is a single sloped roof at 1:12 pitch.
My question now is how can I detail the eave and gable ends of the roof without using an eave strut (i.e. a deformed channel for the lack of a better description "cantilevered" off the column). Is there a way I can use traditional members? My wall girts are 8" CFC that are mounted to the outside face of the columns (again I did this to increase the amount of space inside the building).
Thanks,
M.






RE: eave struts
For girts, why wouldn't you use Zed sections rather than Cee's? They are more economical, because they can be lapped over the supports to reduce the section required.
Connecting cladding to hot rolled channels is to be avoided if possible. Would you be able to get adequate capacity with lapped 6" Zed purlins?
RE: eave struts
I guess I could use z'ss for the girts, but my question is how can I detail the eave and gable ends of the roof. See attached sketch (hope it works, I have never attached anything to this forum before.)
Thanks,
M.
RE: eave struts
RE: eave struts
RE: eave struts
Personally I use a custom welded bracket and pass a channel member from knee to knee of the portal frames, basically perpendicular to your page and connected at every frame. This is similar to what MikeE55 has said, and I would very much encourage you to do this... It does not have to be a folded plate; My personal preference being a custom welded T-section where the base is a shaped "arm" reaching up and out from the face of the column (or rafter; Many people mount this to the top of the beam-column joint).
I'll post a detail if I haven't been clear, however that'll have to wait as I am literally between jobs. *smiles*
Cheers,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: eave struts
RE: eave struts
Your question about the eaves detail indicates that this is the first time you have done this. The purlin member at the eave needs to be able to support the gutter and also provide vertical support for the girts if they are not propped from the floor. So you have to detail a bracket off the column or rafter to support this eaves member. In Australia, we often use a special fascia purlin as the gutter support.
The eaves member for support of the sheeting should not be used as the eaves strut of the bracing system, because it is in the wrong plane. Refer my first post for that.
Metal roofing should not be relied on for diaphragm action. The fasteners are either through the crown of the sheeting, or else as MikeE55 suggested, they are concealed and the roofing floats in clips. Either way, no diaphragm should be assumed. Use a horizonal truss system.
The purlins should be braced against uplift with bridging between the purlins.
I think you need to find some drawings which have been done by others and seek the advice of someone more experienced in your office. It is not complicated, but there are tricks for young players.