Section Classification - RHS

[Anonymous]

Hi,

I am checking an RHS subject to biaxial bending, torsion and shear.

I am wondering why Robot classifies the section as Class 1 (considering the web in shear) instead of Class 4 (web in bending) as shown on Tata website.

Thank you for your help.

Franco

[Artur.Kosakowski]

Hi Franco,

Could you attach the rtd file with this bar? 

[Anonymous]

Thank you Artur.

[Anonymous]

Any updates?

Thanks

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

I'm sorry for not being able to answer you earlier.

For youir set of forces with My and Mz  the critical is the right vertical plate of the profile which slenderness is 36. Robot uses the formulas marked in yellow below:

in your case alpha = 0.727 so with the slenderness limit A1 = 38.11 

hw/tw = 36 < 38.11 class 1.

For pure compression that would be A3 = 42*E = 34.17

hw/tw . A3 = 34.11 class 4

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