ZeroLength Elements

[armkam]

Hi All,

I want to define the interface between soil and shallow foundation.
Suppose the followings are my soil and foundation nodes. Both nodes have 3 DOFs.

Foundation: node 1 0.0 0.0 10.0
Soil: node 2 0.0 0.0 10.0

I want to have frictional behaviour in lateral DOFs (X- and Y-direction) and elastic with no tension in vertical DOF (Z-direction) so it can transfer compression but no tension.
For lateral interface, I want to use zerolengthContact3D and for the vertical one, zeroLength with ENT (elastic with no tension material).
The definition of zerolengthContact3D is:
element zeroLengthContact3D $eleTag $sNode $mNode $Kn $Kt $mu $c $dir
My understanding is the direction of the material should be normal to the directions I want the material to act frictional. In my case this would the 3rd DOF. So I used:

element zeroLengthContact3D 1 2 1 3e10 3e13 0.163 0 3

In addition, for my vertical behaviour I used:

uniaxialMaterial ENT 2 3e7
element zeroLength 2 642 727 -mat 2 -dir 3

Do you think these elements work for as I want in the above-mentioned format?
Also, what are the valid ElemenRecorders for zerolengthRecorder? I've used 'force', 'forces' and 'globalForce' but I only got a bunch of zeros (there is a horizontal shear in the model on the foundation so it shouldn't be zero).

Cheers,
Arman

[selimgunay]

I think you should use nodes 1 and 2 for the zerolength element as well.

[armkam]

How about the recorders of the element (zeroLengthContact3D )?
I cannot record the forces!

[armkam]

An update:

I tested a couple of scripts and the conclusions are as follow:
The zerolengthContact act as a zeroLength element with an ENT material in the direction normal to the frictional plane.
If both the elements are used, they act parallel. Under the same load, the stiffness doubles and the normal displacement halves.