Modeling the spring

[MarTgr88]

Hi,

I would like to connect 2 joints with the spring. I saw a possibility to model it with the link elements, but if I understood right for link elements only coincidential nodes can be aasigned. I have 2 joints that don't have the same coordinates. Is there a possibility in Seismostruct to model spring with the length of 2cm between 2 joints?

Thank you very much!

[huffte]

Hi MarTgr88.

One way, of course, is to simply change to coordinates of one of the nodes such that they are, initially, coincident.

However, if you do need the nodes separated by 2 cm for some reason, I believe you could use the following modeling strategy:

1. Let's call the existing nodes, separated by 2 cm, N1 and N2.
2. Add a new node, N3, having the same coordinates as N1.
3. Define a link element, having the desired spring properties, between nodes N1 and Node3.
4. Define a rigid link between nodes N2 and N3.

Best of luck.

[MarTgr88]

Thanks!

I have tried this, but it is not working.

I am modelling RC frame with infill wall and I want to model springs between infill panel and frame. In SeismoStruct user manual on page 375 you wrote:

NOTE 3: In very refined models, users may wish to introduce link elements between the frame and infill panel nodes, in order to taken into account the fact that the infills are commonly not rigidly connected to the surrounding frames.

How can I do this?

Regards

[seismosoft]

Hi MarTgr88,
You should model things in the following manner:
(node 1) – link element - (node 2) – frame element (node 3) – link element - (node 4)
Note that you can also add rigid links to take care of the size of the beam column joint.
Regards,
Seismosoft Support

[MarTgr88]

Hi,

if I understood right:

- node 1 should be node of the frame
- node 2 should be node coincidental to the node 1
- node 1 and 2 are connected with the link
- node 4 is node of the infill element
- node 3 should be node coincidental to the node 4
- node 3 and 4 are connected with the link
- node 2 and 3 are connected with the rigid frame element
- Infill wall and frame should have offset of 2cm

Can you correct me if I am wrong?

Thanks!

[z.gronti]

Dear MarTgr88,

Lets say that N1 is the frame's node and N2 is the infill's node, that have a distance of 2cm, i.e. the required offset beween infill and frame. You need one more node, N3 that should have have the same coordinates with one of the two nodes, N1 or N2. The two nodes with the same coordinates, e.g. N2 and N3, should be connected with a link element and the other nodes N3 and N1 with a rigid link.

[MarTgr88]

Thank you for your answer.

Is it possible to add springs/links in this way all around the infill wall?

To explain in more details. I would like to model the frame connected to the infill wall with the springs, but with for example 10 springs on each of four sides. In that way, as explained in note 3, the fact that the infills are commonly not rigidly connected to the surrounding frames would be taken into account.

Thank you for your help!

[seismosoft]

You need not to add so many links. Considering that the infill element has 4 nodes and the surrounding frame elements 2 nodes, you can (and need to) do this only at the corners.

Seismosoft Support

[MarTgr88]

Ok. I have done this. Added 4 link elements in 4 nodes. But the problem is that I want to define stiffness of the Link/spring in just F1 and F3 direction, and it seems that in this way infill element doesn't get activated, because M2 stiffness is 0.

Is it necessary to define M2 stiffnessin order to activate the infill element?