## Robot Structural Analysis

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# Re: lifting the construction

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Iam not sure if its okei or not. You can look at the file that i attached earlier.

# Re: lifting the construction

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I would say that something has to be corrected

**Artur Kosakowski**

# Re: lifting the construction

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yeah, I see it now. Whats your opinion of what i should do? If i added a Support in node 1 (RX, RY and RZ) i get as good as zero. Would this be the proper way of doing it?

# Re: lifting the construction

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# Re: lifting the construction

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After we put the soft springs in each of the four corners we still get a wierd reading in the displacements bar under node properties.

See attachment.

# Re: lifting the construction

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I put the springs to 100 kN/m and got rid of the displacements, dont know if thats the best solution. The reactions in the springs is still very low..

# Re: lifting the construction

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as I said before " *your lifting point coordinates (node 71) should be as precise as the CG of the loads on your lifting load case/combination*"

This will not work with several load cases.For each load case you should have a unique lifting support type(UX + coordinates) according to the lifting point coordinates.

If the lifting point coordinates doesn´t match the Loads CG , the sum of the cables horizontal components will not be zero and as consequence you´ll get horizontal reactions on the XY supports and large displacements on the structure nodes

# Re: lifting the construction

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I just wonderd if modelling the cables, lifting the construction, would work but only modelling them half way to there meeting point ( center of gravity) or so and placing a support there for every cable. Then you would get 4 pin supports, and realistic force distribution in your structure with x, y and z forces acting on the corners....

# Re: lifting the construction

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hmmmmm my suggestion:

download Mortels' model from this thread and try! Post the results.

Tony

# Re: lifting the construction

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Hei!

Just downloaded the model and playd with it a little. I did have to place fixed supports at the end og the cables, forcing them to get some moments but placed an release at the connection to the main struture so that the moments wont travel further into the structure. I have not been using Robot for a long time so this may be total fail but this way I think the axial forces from the cables with there angle towards center of gravity will be taken into account without playing with supports at each corner