EqualDOF and axial deformation (please help me)

[jionny203]

uyzagan i tryed the model with element disp for beam and the axial deformation is 0, but the problem on the axial force is not solved.

[divamva]

There are more issues when modeling fiber beams with a rigid diaphragm. The problem is that there actually exists an axial DOF for the fiber beam.

If you completely constrain this axial DOF then you get immediately large prestressing forces that can increase your strength for the fiber sections.

If you remove the axial constraint, then the beams will lose strength and crack or even become develop hinges even under gravity loads.

[jionny203]

I do a model where end node of beam have only same rotations and vertical displacement of end column's node.
the model is:
________o x
| | o node of beam (I call 1)
| | x node of column (I call 2)
| | x & o have the same position
| |
| |

in the model I write
node node
equalDOF 1 2 2 3

And I enforce the same orizzontal displacement of other end column's node.
In this way the axial force in the beam is about 0.
Can it be a solution of problem?

[Selim Gunay]

jionny203,

Using your solution, can you obtain the periods of the original system.

Thank you

Selim Gunay