Made-up section!
Made-up section!
(OP)
Hello,
I need some help figuring out something.
I need to calculate the section modulus for a made up section, namely a circular HSS of 16''x0.500'' with a W10x39 inside (centered), and filled with 5 ksi concrete.
I need this for a soldier pile and lagging temporary retaining wall.
I think I should add the section modulus of both steel section (since it is about the same centered point), and neglect the concrete, am I right?
Thank you very much for your help!!
Jonathan
I need some help figuring out something.
I need to calculate the section modulus for a made up section, namely a circular HSS of 16''x0.500'' with a W10x39 inside (centered), and filled with 5 ksi concrete.
I need this for a soldier pile and lagging temporary retaining wall.
I think I should add the section modulus of both steel section (since it is about the same centered point), and neglect the concrete, am I right?
Thank you very much for your help!!
Jonathan






RE: Made-up section!
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: Made-up section!
If you believe the concrete will bond to all steel surfaces, a better way would be to calculate the section properties of the transformed section.
BA
RE: Made-up section!
- You will have composite behavior between the two steel members.
- You'll likely have composite behavior between the steel and concrete but, unless I needed it badly, I probably wouldn't bother with the effort of trying to account for the concrete with cracking etc.
Whether or not your strategy is appropriate will depend on whether you're using the plastic modulus or the elastic modulus.
- Plastic: add the two moduli.
- Elastic: add the two moments of inertia and then divide by DIA/2 to get the combined modulus.
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.
RE: Made-up section!
As I think I understand it, I think you are correct, it would be the Sx of the HSS and the W10x39 combined, Assuming they have the same centroid (IE the W10 is centered in the HSS). Assuming that you are OK assuming they will act compositely and that the internal shear forces will transfer between the two, which likely isn't a bad assumption, albeit I haven't done this before so I'd have to ponder it some.
RE: Made-up section!
RE: Made-up section!
I just applied parallel axis theorem to Sx...my excuse is that it's Friday...
RE: Made-up section!