Uncouple Axial Force and Moment in beams

[geoStru]

Hello everyone,
is it possible to uncouple, for the beams with fiber section, the behaviour between Axial Force and Moment?
In SAP when introduce a Rigid Diaphragm the axial force in beams is 0, but not in OpenSees.
How could I do to obtain the same behaviour for the beams in OpenSees?

I tried to duplicate the nodes and applied the equaldof but it doesn't work. For example
node 121 $X1 $Y1 $Z2
node 1211 $X1 $Y1 $Z2
node 122 $X2 $Y1 $Z2
node 1222 $X2 $Y1 $Z2

equalDOF 121 1211 2 3 4 5 6 (the beam is along the X axis)
equalDOF 122 1222 2 3 4 5 6

element nonlinearBeamColumn 221 1211 1222 $np $BeamXSecTag $IDBeamXTransf;

[selimgunay]

The most direct way is to compute the moment-curvature externally and assign it to your section instead of the fiber section

[geoStru]

The most direct way is to compute the moment-curvature externally and assign it to your section instead of the fiber section

how can I do this?

[selimgunay]

You can do it using a zerolength section or 1) model a cantilever column, 2) assign a fiber section to it, 3) apply the axial force that you want to compute the moment-curvature for, 4) do a lateral pushover on your column, 5) record the moment-curvature at the bottom integration point

[insap]

You can do it using a zerolength section or 1) model a cantilever column, 2) assign a fiber section to it, 3) apply the axial force that you want to compute the moment-curvature for, 4) do a lateral pushover on your column, 5) record the moment-curvature at the bottom integration point

Thanks.