The OpenSees Community

I have changed the stiffness of the material ($ko) to fix the frequency to the range that I want. I should say that my model's first frequency is a little higher than normal (14 Hz) and to get the model nonlinear without changing gamma and beta I should have a huge factor on my input earthquake record. by the way, the other parameters are: Alpha=0.1, n=2, Ao=1, and there is no degrading of any kind. the main parameters that I have used are Ko, gamma and beta. I suppose that since the BoucWen is just applied on to the fibers, the nonlinearity in a bending element is concentrated on outer fibers and this requires large gamma and beta to produce nonlinearity for whole model.
Is it possible to use boucwen in another way, like for beamwithhinges and as force-deformation.

Thanks,

Hi,

I have a simple 3DOF model. The first element is nonlinear Beam Column element with fiber section. I used BoucWen model for material nonlinearity, but to get a nonlinear model I should increase gamma and beta enormously; like Gamma=beta=1e11!
Do you think it is acceptable to have such values for these parameters?
The first mode frequency in my model is 14 Hz, and it is excited by VanNuys earthquake.

Thanks,

silvia wrote:
> yes. you can use materials to define any
> "force"-"deformation" responses, such as
> moment-curvature, for example.
>
> i almost want to change the name to something else.

So, Is it Possible to use the Pinching4 material model with fiber section? I mean Can we assign it to fibers like stress-strain instead of force-deformation?

Thanks,

Me too, I cant download

I have the same problem,

I modeled a simple 7DOF system with BeamColumn elements. I restricted all DOFs except the DOF 1. I expected to have the stiffness matrix of a shear building and calculated the eigen frequencies. they are not what I get from opensees as modal frequencies. But when I model the same system with axial elements with the same stiffness the modal frequencies are the same.

What is the problem, is OPENSEES modeling the the system with BeamColumn element more flexible (modal frequencies are less than what is expected).

I have a problem with Beamcolumn element. I modeled a simple 7DOF system with BeamColumn elements. I restricted all DOFs except the DOF 1. I expected to have the stiffness matrix of a shear building and calculated the eigen frequencies. they are not what I get from opensees as modal frequencies. But when I model the same system with axial elements with the same stiffness the modal frequencies are the same.

What is the problem, is OPENSEES modeling the the system with BeamColumn element more flexible (modal frequencies are less than what is expected).

I can't download BuildingTcl. the page is not working !