Decoupling moment on column

[Anonymous]

Hi,

I have a query on the attached model.

For load cases such as  LC 1 (this is in the example below) in which only vertical load applies, I am seeing that the moments at the central cantilevesr due to the vertical load produces different push/pull reactions on the supports (FX forces) - image at the bottom.

Seeing the bending moment diagram, it seems that the cantilever moment is not taken equally by both parts of the column, so for the central cantilevers (-44.85kNm) the top part of the column is taking more momen (21.21) t than the bottom part (25.52). therefore these moments are producing different reacions when they are decoupled.

There is a part of the difference in bending that is missing and it could only go in torsion (which is not happening). Could that missing moment be being taken by the slab? If this was so what can I do to release it from not taking it?

Many thanks,

M

[Artur.Kosakowski]

Try to delete the support from node 9.

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[Anonymous]

Hi,

I have deleted the support at node 9 but still getting the differences on the push/pull forces.

Could the slab by any means be taking part of the bending moment? It seems there is a redistrubution of moment to the external columns.

Thanks,

M

[Artur.Kosakowski · Accepted solution]

You need to have a symmetrical model.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

Hi

thanks for the  quick response.

Did you get rid of part of the structure ?. I have made all the columns the same and the model is symmetrical now but  I am not getting the same push/pull forces yet (though their values are much closer now).

[Artur.Kosakowski · Accepted solution]

I'd say the railings are on the top side only 🙂

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.