Flatsliderbearing for 2d 2dof model

[cgtydmrc]

Hi,

Could you please help on what is the possible way to include base isolator (for example, flatsliderbearing) into a 2d 2dof model?

Thanks,
C.

[Jhno]

Zerolength element ?

[cgtydmrc]

I know I can use zero-length element or two-node link element with a finite length. However, the problem is while all the nodes in my model are 2dof, the nodes that I connect a flatslidebearing element require to have 3dof. Therefore, my question to you is that have you ever utilized flatsliderbearing element in a 2d 2dof model before?

Thanks.

[selimgunay]

You can use it for a 2D problem, please see the descriptions and examples in the below link

http://opensees.berkeley.edu/wiki/index ... ng_Element

[cgtydmrc]

Selim hocam merhabalar,

My models consist of 4 node quad elements with 2 dof per node. However, the flatslidebearing element requires the nodes to have 3 dof. That is why it creates a problem when i try to place the bearing in my model. To connect two different models (for example 2d 2dof and 2d 3dof) I employed equal degree of freedom multi-point constraints. I believe it works in the same way, but is there an other way that this bearing element works also in a 2d 2dof model?

Thanks in advance,
Cagatay

[selimgunay]

Cagatay merhaba,

I think you can fix the rotational DOF. It seems this is what is done in the examples in the wiki page.

http://opensees.berkeley.edu/wiki/index ... er2d_2.tcl

[cgtydmrc]

Selim hocam merhabalar,

I modelled the bearing element in the way I explained above and it gives a warning such:

WARNING FlatSliderSimple2d::setUp() - element: 300 - ignoring nodes and using specified local x vector to determine orientation.
WARNING FlatSliderSimple2d::setUp() - element: 301 - ignoring nodes and using specified local x vector to determine orientation.
WARNING FlatSliderSimple2d::setUp() - element: 302 - ignoring nodes and using specified local x vector to determine orientation.
WARNING FlatSliderSimple2d::setUp() - element: 303 - ignoring nodes and using specified local x vector to determine orientation.

And it gives a structural period of 7.86 seconds for the first 5 periods same. The fundamental period of the building was 0.29 s without the slide bearing element. Do you think this is okay? Or too much difference which happens because of a wrong assumption in the model?

Thanks,
Cagatay