Use Effective Lengths Determined by Buckling Analysis in Code Design Checks

[anthonymctigue]

Afternoon All,

I am relatively new to Robot so apologies if this has been asked before.  I did look through the past posts on this topic but could not find anything that matched 100% exactly what I am trying to do.

I am trying to do some structural analysis and design of some lightweight steel sway frames made from non-standard, bespoke steel sections in order to achieve the required architectural finish.  The architect's brief is to keep the columns to a maximum overall dimension of 150 mm by 150 mm.  We recently moved from Microstran to Robot which had within it the option of carrying out a non-linear buckling analysis and in turn taking the effective length results from that buckling analysis and using them in the code checks to determined compression/compression and bending code checks.  This provided us with good answers compared to using the effective length factors from Table 22 of BS 5950 or Figure 4.6.3.2 of AS 4100 as they were less conservative and thus allowed us to implement Appendix E of BS 5950 whereby if certain conditions are satisfied then we can adopt the effective lengths determined from a buckling analysis in lieu of the conservative values from the code.

In Robot, we have carried out the non-linear buckling analysis on the columns and obtained similar results however, the effective lengths used in the code checks do not appear to match those obtained from the non-linear buckling analysis.  We have implemented the automatic buckling length as per the help file link below but it appears that this determines the buckling lengths based on the relative stiffnesses of the connecting members and end conditions as opposed to the effective lengths determined by the more rigorous buckling analysis.

Does anyone know if this is possible and if so, how to implement it?

Thanks,

Anthony

[Artur.Kosakowski · Accepted solution]

Hi @anthonymctigue

In Robot there is no option for automatic assignment of the buckling lengths to elements of a model based on the buckling analysis 

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.  

[anthonymctigue]

Hi @Artur.Kosakowski,

Thanks for your prompt response.  Pity it is not the answer I was hoping for but at least it is clear what I need to do.  Is this the type of functionality that Autodesk may consider adding into Robot in future releases?  It seems a bit of a waste to have the facility to do a buckling analysis but not be able to use the results for design purposes.

Anthony

[Artur.Kosakowski]

Hi @anthonymctigue

I'm sorry but I'm not in the position to provide any information on the future development of RSA but I'd love to see this feature in RSA too.