Curved Rafters
Curved Rafters
(OP)
Dear Colleagues,
I am looking to design some small portal frame buildings (open sides). The client has asked that the roofs be curved (i.e. barrel vault design). Are there any references out there that deal with the design of curved rafters in regards to determining the effective length for lateral torsional buckling? I am not sure what (if any) special considerations are required due to the rafters being curved.
Example of curved rafter (by others):
http://valentineengineering.com/valentineengineeri...
Appreciate your thoughts on the subject.
Regards Jake
Australia
I am looking to design some small portal frame buildings (open sides). The client has asked that the roofs be curved (i.e. barrel vault design). Are there any references out there that deal with the design of curved rafters in regards to determining the effective length for lateral torsional buckling? I am not sure what (if any) special considerations are required due to the rafters being curved.
Example of curved rafter (by others):
http://valentineengineering.com/valentineengineeri...
Appreciate your thoughts on the subject.
Regards Jake
Australia






RE: Curved Rafters
Link
RE: Curved Rafters
RE: Curved Rafters
My purlins will also be fairly closely spaced, although I would prefer to reduce the amount of fly bracing required for aesthetics. Its mainly uplift I am concerned about when there is compression in the bottom flange.
Many thanks,
Jake
RE: Curved Rafters
I'm interested to see what you come up with for the effective lengths. Did you see that the bending section said it did not cover portal frames?
If anyone else has a reference with an AS4100 flavour that would also be much appreciated!
RE: Curved Rafters
RE: Curved Rafters
I have designed both Glulam and Steel for curved arch support, but have never done cost comparison. Anyone have any info on this? I have been in more of a 'do what is requested' position, but may be asked for cost advice on this eventually.
RE: Curved Rafters
Appreciate the help.
Regards Jake
RE: Curved Rafters
RE: Curved Rafters
Like 90% of what I have been quoting on lately - I still haven't got the green light from the client to do the detailed design.
I managed to undertake some preliminary member sizing using the literature you put me on to (thanks for that). This allowed the client to get an estimate to fabricate and I suspect the $$$ were more than they were expecting.
Things seem very quiet on the structural front (Queensland, Australia) at the moment so I hope a few of these smaller jobs come off eventually.
Regards Jake
RE: Curved Rafters
Thanks for the update. I just found curved steel and the associated stresses interesting.
RE: Curved Rafters
I remember deriving the shear forces, axial force and bending moment equations for a catenary shaped beam in university and had a few big 'aha' moments when it all came together. I suspect the same would occur for a curved beam if I were to go back and examined it from first principles.
RE: Curved Rafters
That and the flailing AUD.
RE: Curved Rafters