Stainless steel design 1

[SKJ25POL]

I designed a short beam 38" from a regular channnel (c 8 x18.75)- bending and an angle in tension (L 3 x3 x 3/16) , if we use stainless steel are these sizes not good?

Is a section property and dimensions diferent for a stainless steel? Or we can use AISC tables for stainless steel channel section?

Thank you

 

[JStephen]

Yield strength, ultimate strength, and the ratio of the two are different with stainless steel. Allowable stress equations in AISC are all set up for carbon steel, probably not drastically different for stainless, but would be some.
You may or may not find channels available at reasonable cost. For a short piece, it may be cheaper to build it up from flat bar or angles.

 

[mike20793]

There's an AISC design guide for stainless steel. It mostly refers back to AISC 360, but there are a few differences other than what JStephen mentioned.

 

[Once20036]

AISC has published a stainless design guide - available on their website.
I would consider member sizes and dimensions to be the same.
JStephen has mentioned some of the differences that impact design.

 

[smb4050]

Probably okay if you're needing a ballpark value or have ample excess capacity. I'm guessing for the short pieces you're need, the shapes are cold formed (bent). What grade stainless? A304 Fb is 33ksi, so nearly the same as ASTM A36. Unless you have fairly thick material, I suspect using hot rolled steel for section shape properties will overestimate the stainless shape by more than you expect. If you have access to AISI cold form steel manual, look for section properties in it, or find a HSS shape and use half of it or calculate it.

 

[EngineeringEric]

Yield strength of 304/316 is much less (304 => 31ksi and E=280000). The AISC Design guide treats the design of SS similar to Aluminum which is different than Carbon steel AISC. If you are welding you should specify different grades (304L i think) and then you have your connections. The design guide goes through all of this.

If you have well in excess of capacity don't worry, if you are designing to 80% with A36 basis... I'd confirm stresses.

FYI Design guide 27 Structural Stainless Steel

 

[DBronson]

SKJ25POL:

A catalog I have from a steel supply center shows an 8" x 4" x 3/8" stainless channel weighing 20.00 lb/ft. This appears to be slightly different from the section you mention. I'd call a steel supplier in your area to see what's available. They'd also have the exact dimensions for these sections.

Regards,

DB