hi i try to fight whit instability type 1

[vanvan11]

good day evryone

i have a problem whit robot.

my model is hanging web (2d) and when its only vertical loads evrythink is normal

when i use wind load (horizontal) + make the middle profiles truss bars to not take bending moments results are good but robot give me istability for evry point of web.. pls help and sory for my bad english

the structure is something like sail or sheet

[Rafal.Gaweda]

First check what the Truss property is:

http://help.autodesk.com/view/RSAPRO/2015/ENU/?guid=GUID-DC397CD9-D82D-4E9A-BF5B-2E83F5459695

It means these release sare useless on these truss members

And your structure is a meshanism. All shown in red members below are truss members so the structure is unstable in all the nodes displayed by Verification. You need to block somehow UX displacement in these nodes or instead of truss property use correct releases to prevent structure for being unstable.

[vanvan11]

10x for fast respons

i try to make it whit correct releases and no truss bars

so for vertical bars Ry and for hotizontal bars Rz is taht whats you mean

This method result is robot give instability this time type 3 only in contour nods and only for vertical bars but results and ratio of bars is ... at least not normal ratio = 1000000 and more 🙂

[Rafal.Gaweda]

so for vertical bars Ry and for hotizontal bars Rz is taht whats you mean

More less yes.

This method result is robot give instability this time type 3 only in contour nods and only for vertical bars but results and ratio of bars is ... at least not normal ratio = 1000000 and more 🙂

I do not undestand. File please.

[vanvan11]

here is the file not calc couse MB

[vanvan11]

whats wrong

is this computable

in first version of my model, middle bars are truss and they have no  at least i get some realistic stress results but deformation was not correct and instability type 1

whit releases all results are creazy

sorry for disturbing you

[Rafal.Gaweda · Accepted solution]

You can not apply releases on bars free ends.

Correct defintion of relases on your model:

[vanvan11]

10x this fix the problem whit instability 

i just forgot to make no releases on free end

10x again for explaining me about releases understandable

i usually use sap2000 and now learning robot. 

! but the resuts are still strange ! what means ratio 10 000K on member vert!

[Rafal.Gaweda]

Why? Check Displacements and Rotation in case 3; look at deformation diagram etc