Frame Analysis - Missing torsional modulus

[Anonymous]

Heya Folks,

I discovered that the Australian standard for steel sections in the CC (content centre) was incomplete and decided to fill it out with some more data. 

In paticular when using the frame analysis with AS sections it kept giving me errors about torsional modulus is zero!

I created a copy of the CC steel section family and input the missing values for polar and torsional modulus.  I even mapped the new columns to the Jk and Wk parameters.  However when I created a new frame with the new family, I still get the same error of "torsional modulus is zero" and I must manually input the values into the beam properties dialogue box labelled Wz.

If anyone has any experience dealing with frame analysis using custom beam sections please let me know the trick!

Hopefully I can then share this with any other AS users once working.

Best Regards

Carl

[JorgenBjornes · Accepted solution]

Frame Analysis doesn't use CC profile parameters but calculates them. For hollow profiles Frame Analysis have no equation to calculate Wz parameter. Therefore this parameter is always zero for custom profiles. For standard hollow profiles is Wz value cached in XML file. Also new custom profile is added to the cache but with zero value for Wz. One way to fix this is to manually add the Torsional module manually in the  Simulation browser.

If you like to dig deep, you can also replace zero value by correct one in that XML file (C:\Documents and Settings\username\Application Data\Autodesk\Inventor  2011\Simulation\Data\sectionProps.xml) 
and create new simulation.

[Anonymous]

Thanks for the clarification.

Yet another brilliant but not quite finished tool....  (last gripe for the day 😉

regards

Carl