Shear stress due to torsional moment in SS-EN 1993-1:2005/AC:2009

[SEAAWSP]

I've found that small torsional moments give unreasonably large shear stresses. When controlling against hand calculation, the Robot value for shear stress due to torsional moment is roughly 10x larger. Or is there something I'm overlooking? See attachment for an example. Hand calculation gives a shear stress at about 20 MPa while Robot gives 208.6 MPa.

[Artur.Kosakowski · Accepted solution]

Which database is this section from? The largest from the UKST as far as I can see is 300x300x16 and the stress due to torsion is 13 MPa. For the user defined structural tube 300mm x 300 mm x 20mm it is 11 MPa Could you attach this example?

[SEAAWSP]

It is a user defined section, a modified SHSC UK section.

I had not checked "Torsional constant" under results in Section definition. Does this mean the defined section did not get a torsional constant assigned?

I'm afraid I can't attach the section file, the site won't allow me to. Something about the file content not matching the file type.

[Artur.Kosakowski]

Try to zip it. You should mark the IX calculations (also other check boxes below it) it as well as select the appropriate section type (structural tube instead of "?") and provide the corresponding information about the dimensions while saving it to the user section database. 

[SEAAWSP]

It is solved! The error was in the section definition - when saving section to database no section type was selected which ended up giving the section flange and web thicknesses equal to zero.