Springs for soil-structure interaction simulation

[Marta Mateus]

Dear seismostruct,
I would like to model a retaining wall and I would like to simulate the soil-structure interaction by using horizontal springs defining its stifness similar to k0*Pv only in the perpendicular direction of the wall. Is it possible?
I wasn't able to define it with the "link element types", but I belive that is the way...I just don't know how.
Could you help me please?
Thank you
Marta

[seismosoft]

Dear Marta,

The modelling you describe should indeed be feasible, using link elements with k0*Pv stiffness values in the horizontal degree-of-freedom and zero values (or small, for increased numerical stability) in the remaining five local dofs.

Seismosoft Support

[Marta Mateus]

Dear seismosoft,
Thank you for your answer.
That was exactly my way of thinking, but for any reason I wasn't able to define the element conectivity of the spring. The nodes are correctly defined, I think:
1 (structural node)
1 (structural node)
12 (non-structural node defining orientation of axis 1)
23 (non-structural node defining orientation of axes 2 and 3)

1 (0,0,0)
12 (0,1,0)
23 (0,2,2)

Before that I've defined a Link element:
F1 - ssy_pi (k0=10000)
F2 - lin_sym (k0=0)
F3 - lin_sym (k0=0)
M1 - lin_sym (k0=0)
M2 - lin_sym (k0=0)
M3 - lin_sym (k0=0)


I've read the information in the help system in this matter and I can't find out what I'm doing it wrong.

Please help me.

Thank you,
Marta Mateus

[seismosoft]

Marta,

Are you using the same node (node 1) twice in the definition of the two structural nodes? This cannot be, of course, you need to use two different structural nodes, with the same coordinates.

You may also try using a small stiffness value (e.g. 1) instead of plain zero for the free dofs.

Seismosoft Support

[Marta Mateus]

Thank you so much!