Hi! I am writing a research paper about lateral-torsional buckling with timber structures and I had a question about a topic discussed on your website: Lateral-Torsional Buckling in Timber Construction | Theory.
In this article, the formula for the Effective Length Considering Elastic Rotational Spring, Restraint, or Member Elastic Foundation is given, this formula is from the German national annex so I'm unfamiliar with it.
In the factors alpha and beta are the springs/foundations Ky, KG and Ktheta. I am wondering how these are determined.
Since Ky is measured in N/mm2 it seems like it's an elastic foundation over the entire length of the beam (N/mm / mm). In my case I am looking at prefabricated roof elements, so Ky would be the battens, fastened at the top of the beam. I would expect a different behaviour from multiple lateral springs with a stiffness in N/mm compared to an elastic foundation over the entire length of the beam.
Moreover, calculating the stiffness of the batten (or rather its staple connection which seems to be authorative) is another question in itself.
I hope you could share some insight in how these springs/foundations should be approached within the framework of roof elements.
Thank you in advance.
