L section (equal angles) of class 4

[Jummybear]

Hi,

When i use L section of class 4 and run calculation of steel/aluminum design robot show me a massage like "members bla bla bla have been calculated as members of class 3. Why? 🙂

[Rafal.Gaweda]

This message appears normally in a situation of relatively low load component for class 4
This follows from the application of rule 5.5.2. (9).

[Jummybear]

my question is still without answer. Ok, it appears in situations of relatively low load and then robot take into account class 3, right? But first of all my load is not so low, and secondly, is it possible that robot takes into account equal angles of class 4 in some cases (with bigger load)?

[Rafal.Gaweda]

Send us model

[Jummybear]

I can send you a model, but it doesnt explain the situation (my model is typical tower structure of L sections). I just tried an example with L120x10 (class 4) like a very short column (0,2m) which do not have any danger to loose its buckling resistance, but i put an axial force to obtain a maximum streeses or near it. It also calculate like a section of class 3 instead of class 4...

If  we look at p. 5.5.2 (9) of EVS-EN-1993-1-1 (your quatation) then its wrote that we can take class 3 in consideration EXCEPT as given in 5.5.2 (10), and p 5.5.2 (10) is about buckling resistance of elements, where sections of class 4 exist and its area = Aeff.

Finally, can you bring me an example when robot calculate section of class 4 as a section of class 4 with real area Aeff?

[Artur.Kosakowski · Accepted solution]

Ilja,

Currently Robot calculates angles of class 4 as class 3 (this is the limitation of the program). The possibility of calculating them as class 4 is on the wish list for future versions.

I'm attaching the class 4 example.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Jummybear]

Now its clear for me. Thank you for reply, Artur.