hi guys,
I get some abnormal bending moment for some of the elements in my model (see attached picture). As I found out on the forum, it has something to do with linear release. but when I try to add linear releases to panel, I get type 2 and type 3 instablity. I have attached a test model. Thanks in advance.
Mohamed is right, many of your instabilities is coming from a too large number of release. Analyse your elements, at one node you have to let at least one element blocked for each dof otherwise the problem is unsolvable.
example : 3 in plane bars intersecting in one point (like 1026) cannot be released at each end.
Then if your still have problem -> post your corrected model.
Thank for the answer!
I just want to illustrate hollow-core slab in the model, which spans one-way and have pinned-connection to supporting beams. I have modeled this configuration in other FEM programs and I get correct bending moment with parabol shapes, but in Robot, I have not succeeded to get the correct results. I followed t.sautier advice and, but still I can't get a parabol shape bending moment. for example, look at the bar 1341 of the attached model.
Model without significant instabilities (supports and some bar releaeses corrected) attached
Results as follows (if you want different results , apply different correct releases) :
Rafal, how did you set the pannel properties in order it is not working with the beam ? I mean it seems that you don't have this "saw tooth" effect on the moment as Tony mentionned in one topic.
Linear release Ux ?
Oki doki.
Works fine.
But the pannel is working with the beams in this model as a composite section.
I say that because I'm not sure that he is aware of that.
Shall have spare Ux release on pannel edges if this effect has to be suppressed
Shall have spare Ux release on pannel edges if this effect has to be suppressed
Your choice. But do it in the way not to make model \ panel unstable.
Which not an easy part when you have a big number of pannels ... have to be wise when you built up the model.