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Hello,
i am working in a model that combines rigid links to introduce the forces with unidirectional releases.
Apparently analysis seems to be correct at the bottom of the structure.
The problems are related with deformed shape at the top of the structure, as show next:
Can you explain what is happening?
Thanks,
DFI
The beam 19 is disjointed (case 7) from short elements because of unidirection releases defined on short elelemnts.
You may see in in Displacement table - uz values in these nodes.
Rafal Gaweda
Hello,
The main question is how can this nodes presents positive displacements with applied loads (descendent loads).
DFI
This situation (in case 7) is in fact unreal because beam 19 in this case is weightless and then tube is not pushed to the rest of structure.
So it is suggested to set this case as auxiliary and use it nonlinear combination(s) considering selfweight of this tube and \ or load applied to this tube
But the explanation is:
loads in case 7 make the nodes 46 47 51to54 to move downards ; the releases at top nodes of these short elements create connections between beam 19 and top nodes when compression in connections occur; top nodes moving downwards produce tension in connection so releases (working on compression only) disjoin beam 19 from the short elements; so in fact every state \ location of beam 19 is correct from calculation point of view ; even falling down to ground level 😉
Hope it is more clear now.
Rafal Gaweda
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