I have modelled a timber structure and the message "separate structure" appears but there is no such an issue. After I trimmed the beams that supposed to be continuous and not interrupted by the crossing beams (see the colored member in the attached picture) the message didn't appear again!
Can you explain it?
Assuming that you set model generation parameters in such a way that there is no calculation node generated at the intersections of the beams the reason is obvious (trimming as I understand your description generates physical nodes at beam intersections). Perhaps you should consider using compatible nodes instead.
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The way i created the continuous beam is as follows: i firstly defined the beam between the two columns (with no any extension of beam out of the columns). Then, i copied the column at each side and then extended the beam untill the new (copied) columns. After i deleted the new columns and the continuous beam was done...
I did that for one beam and then i made a translation (copy the beam with some repeatations) in order to create the whole roof. I finally found out (while writing this post..) that the message about "separate structure" occured because of that repeatation and also because the new created continuous beams (made after the repeatation) were not crossing columns but crossing beams. I shoud do the 1st "manual" way of creating continuous beams, for each case separately ..
Compatible nodes are useful (as it would be the precise way in this case indeed) but it is not always a practical way..