Hello everyone,
I have a question about the bi-axial bending and torsion calculations in StaadPro based on EC3.
I designed a beam (RHS) subjected to bi-axial bending and torsion. I am comparing my hand calculations with Staad pro unity check but when i define the torsion check in Staad, member looks failing even it is not failing in my hand calculations. When i remove the torsion check, i get same result based on only bi-axial moment check. I investigated the problem and i have seen that StaadPro uses SCI057 but according to SCI, this publication is replaced and new calculations for the beams subjected to bi-axial bending and torsion should be done according to SCI P385 cl.3.1.2. According to this clause, bending moment capacity of the section in both direction should be reduced due to torsional effects and (My,ed / My,rd)^1.66+(Mz,ed / Mz,rd)^1.66 forluation should be used to check cross-section for RHS.
Is there something that i miss when using clause 3.1.2. in P385 or do i need to make an update to update StaadPro torsion calculations based on new publication SCI P385?
Thank you very much in advance.
Ibrahim