Aluminum tube dome roof connections/design
Aluminum tube dome roof connections/design
(OP)
Once again I pusing the limits of my knowledge and I need some direction. I have modeled a 56' diameter dome 11' high in RISA which is to be constructed of Aluminum for corrosion resistance. 20 segmented arches connected with x bracing. Every member is angled and twisted. The structure will be supporting an existing fiberglass dome which has not completely failed yet, the snow is coming though. It is a clarifier cover so no field welding due to methane. So far I have a 4kip frame dead load after a lot of work. I have the 2005 Aluminum design manual to check my model with but I am not sure about the tubular connection design. Should I approach these connections as if designed with steel (using AISC tube steel design methods) using the properties of Aluminum or is there another reference which would be more appropriate. I'm trying to avoid building a FEM of each connection as my fee will certainly not cover that.
thanks
Paul Irwin PE
RiPPLE DESiGN STUDiO
thanks
Paul Irwin PE
RiPPLE DESiGN STUDiO






RE: Aluminum tube dome roof connections/design
RE: Aluminum tube dome roof connections/design
1. Model the structure with aluminum material and standard shapes in risa (RISA will include aluminum next year, but connections are a different animal)
2. Check the members using the Aluminumn Design Manual including any reductions of strength at welded areas and reductions in stiffness per ADM
3. Design the connections using the material properties per the ADM05 and steel connection design procedures per AISC.
Without any specific literature, known to me, regarding aluminum connection design methods, this seems reasonable. The connection design procedures are based on mechanics of materials and as long as I perform the required checks, with the correct material properties, I should be ok. Again, if there is a published connection design procedure out there that I should use, that is what I need.
thanks
RE: Aluminum tube dome roof connections/design
RE: Aluminum tube dome roof connections/design
Maybe try to standardize your connections and FEM a few of them...
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RE: Aluminum tube dome roof connections/design
I have been trying to standardize the connections and that is another challenge. It's a fun one. The owner and contractor rejected the geodesic option. Perhaps I should have sold it harder. Bucky rocks.
RE: Aluminum tube dome roof connections/design
RE: Aluminum tube dome roof connections/design
As someone noted, the allowable stress on welded aluminum is significantly reduced. Again as an example, the 6063-T6 material within 1 inch of the weld has an allowable bending stress of 6.67 ksi....BIG REDUCTION! While that does not actually happen, it has been used by the AA for many years due to the variation and lack of predictability of the post-weld strength in the heat affected zone of the weld.
RE: Aluminum tube dome roof connections/design