RFEM - the effective length is not defined

[Pretty Girl]

Why these errors occur? This is a very basic structure to test the software. I did their steel hall tutorial as well before which it ran smoothly without any errors and at that the RFEM didn't ask to set effective lengths manually.

I just drew four legs, on top of the drew another four legs, connected those with beams and bracings and put hinged support. When I click the analyze button, it throws these errors.

Why don't it just automatically calculate the effective lengths etc. Or is it saying some other thing that I should have done?

Tension braces are also just steel beams (I just wanted to test it without wasting much time)

 

[strucbells]

I don't know this particular program (most of my modeling has been in RISA3D), but usually these types of errors are related to defining your member end releases (ie if the connections at the ends should be modeled as fixed or pinned) and the continuity of your members.

I would draw the columns in as continuous members rather than breaking them at the intermediate level, and put in the member end releases for all elements other than the columns as pinned, and re-run. Usually you will need one member at a joint that does not have end releases for stability (even if it is a pinned condition).

Also you may need to define your bracing members as braces and your column members as columns so that the program knows how to treat them correctly.

 

[KootK]

Why don't it just automatically calculate the effective lengths etc.

Because that's analytically impossible without getting into an advanced buckling analysis. Most FEM packages used in production structural engineering environments are the same way. It's a feature in the sense that it encourages designers to exercise their engineering judgement in one of the few meaningful ways that is left to them nowadays.

It sounds as though you are a pretty girl with rather limited patience.

If you are seeking FEM software that indiscriminately analyzes whatever chicken scratched thing you draw in thirty seconds or less then, truly, I hope that you don't find it.

 

[Just Some Nerd]

Perhaps a bit too discourteous for my liking, Koot. PG's posts typically give me the impression of lack of experience and the absence of someone who can provide meaningful guidance or a complete understanding of things, hence their presence here on the forum. In this case it seems they've done a tutorial and are playing around with the software to gain an understanding, so I wouldn't be so quick to judge. I think they're being quite literal when they are asking why the software can't calculate certain things on its own even for a very simple structure, it's not something I'd have figured out my first time using say Spacegass - I didn't know jack about the limitations vs capabilities of that variety of software, I was just a grad at the time trying to be productive.

 

[KootK]

so I wouldn't be so quick to judge.

Quick to judge? We've had a steady stream of day zero level questions from Pretty Girl for the better part of three years now. Three years. Even in a complete mentorship vacuum, it shouldn't take that long for a motivated self learner to find their feet with respect to the basics.

Moreover, I've always suspected that Pretty Girl's handle is a version of catfishing. Bait a bunch of pasty cubicle dorks into giving him more than his share of team resources and serving as his white knights when needed. I find it offensive and unprofessional, even for the internet.

Am I making some assumptions from afar here? You bet. Sue me. I call 'em like I see 'em.

 

[STpipe]

Without knowing the details of the model, it sounds like you inadvertently deactivated/deleted something that impacts the stability calculation. By default the program should be setting the effective length as the length of the member (which can be very wrong, but at least there is a starting point), and if it's attempting to calculate Mcr using a buckling analysis, by default the program should be setting boundary conditions at each end of the member, so it should give you a result, even if the result is inaccurate from a stability perspective.