HSS ROLLED TO A RADIUS

[sedesigner06]

I have some pretty healthy tube sections (20x8x1/2) for a canopy roof. The architects desire to make the roof curved. Are there any references out there that recommended the tightest radius that the tubes can be rolled too. I am assuming they roll them in a similar way they camber a beam and heat up portions of the tube.

Thanks in advance for any help!

 

[dhengr]

Sedesigner06:
There are a number of steel fab. companies doing this kind of bending. Get in touch with a couple of them, and given your approx. member size and geometry, ask them what they can do. Your initial design and analysis hones in on the member size, then the issue becomes can they do that bend length, radius, etc. without buckling and deformation problems in the final members. The companies with experience can do some amazing things with steel members. Look in the steel mags. for ads by stl. bending folks, talk to your local fab’er. about who they would go to, call AISC for a list of stl. bending members.

 

[KootK]

I second the "call around" approach. The attached article may also be helpful.



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.

 

[sedesigner06]

I did the call around approach. The hss 20x8x1/2 can be rolled to a radius as right as 50' without any issues. I also have a series of hss 4x4 that are rolled to a tighter radius of around 35'. The fabricator said that is a the lower range capable with the "rolling machine" and to keep the wall thickness as thick as possible to avoid the wall crippling. He said that tighter radius's are possible but require heat bending which is around 5X as expensive.

Thanks for the input, thought I would pass along the information I was able to gain on the subject matter. Good day!

 

[dhengr]

Sedesigner06:
Thanks for the update. We all appreciate the fact that you took the time to come back and let us know what the outcome was, after we spent our time trying to be helpful. This kind of exchange and update is part of what makes E-Tips work so well, and be so successful in helping engineers, help other engineers. Sometimes we are left with the conclusion that after posting and getting a half dozen meaningful responses, the OP’er. must have changed professions and become a beautician or something else unrelated to engineering, because we never hear from them again.

 

[racookpe1978]

Remember! ALWAYS tell the shop when you call for "can yo do this" the member size (designation and wall thickness, member length and radius (affects whether he can lift it (total weight), move it through the rolling machine the right way, lift it out of the rolling machine after rolling (that it is not binding on wall, structure, roof, other machinery nearby) and that it will be fit in the machine at the machine's rated capacity.

You MUST also tell the fab shop the direction of the roll: easy way (rolling the short side or short web) or hard way (rolling the longer web or longer side. They should ask. But they may assume you know they cannot roll a 20 inch web, but can do a 4 inch web or height.

 

[BadgerPE]

If it is important to you, maybe call and talk with a few more fabricators. The top chords (12x6x3/8) were rolled to a radius of 24'-5" for us on this project.

 

[sedesigner06]

Thanks for the input, after I complete my schematic framing I am thinking it will be a good idea to tabulate a spreadsheet with all the information for my radiused members and coordinate with one or two fabricators.

Thanks for the picture (they really are worth 1,000 words sometimes. This is similar to what I have going on with my canopy (radius members with members cantilevering).