Seismosoft | Earthquake Engineering Solutions

by defining nodal constrarints in 2d models in eigenvalue analysis resulting periods are very very over and meaningless
i trid many steel moment frames and all types of constraints but there was not any improvment.
what's the problem? is there any alternative?

As stated in the Help System, the indiscriminate introduction of diaphragm constraints in fibre models can lead to erroneous results, due to the artificial over-stiffening of beams (which are restrained against axial deformation).

In principle, however, such effect should not be observed in eigenvalue analysis, where no axial deformation of the beams is occurring, hence perhaps there is something else that is wrong there.

Send us the model (in an as simple as possible version) so that we may have a look at it.

Seismosoft Support

We have looked at your models, corrected some errors, and ran the analyses with and without constraints; the results were identical.

Seismosoft Support

I have the same problem how can i send my model? and if you can say what were the errors in mortezarazi's
model so i can myself fix them in mine?
thanks

Hi,

You can send me the model (try to send it as simple as possible).
I can take a look and give you my feedback.

Cheers,
Romain