I would like to discuss with you about the direction Adonis should take (personal opinion...Adonis is a wonderful project).

In my opinion Adonis should be more FEM friendly and less "user friendly" or let me say more "user aware software". I think that there is no need of having cable, tie-back and strip element, they are basically truss element with different initial conditions (full length bonding, pretension and so on), I will add interface element (which probably you already use for bonding) with which you can model, for example, the coupling/contact between a sheet pile wall and the internal wall of an underground station or the interface between a wall and a soil mass.

In this way the user is forced to know what he is doing and still Adonis will remain a user friendly software with pre and postprocessing, automeshing and so on.

What do you think?

It is just a personal view on FEM software.

there is no interface element involved cable/tieback and strip elements are 1D elements that connected to the element using spring/slider (please take a look at UDEC/FLAC manual if you are interested on formulation) at their node. like some open source FEM program I don't to leave everything to users and force them to use several spring and trust combination to do the work which is usually prone to error. I want to avoid this by simply creating a package to do the dirty work for the user and make the painful process easy. so to answer you question I want to have "user friendly program" as you said but at the end still its going to be "FEM friendly" too.

ok, with interface i meant (for a fast misunderstanding it seems  ) a "coupling" between elements, it was not directly releated to a proper interface element or to a coupling with springs.
Indeed you already coded this type of coupling but if one want to use it to model friction between sheet pile wall and soil mass.
Maybe we can use a workaround by creating a small soil layer between soil and wall but, in my opinion, it could lead to numerical instability due to smal thickness and high shearing.

Anyway that's ok, I understand your point

sorry misunderstood your comments. yes I'm currently working on interface element. the formulation is easy (I've done it several time for different projects) the main and most time consuming part is the pre and post processing. unfortunately I'm not expecting to be released sooner than three months so I think it's a good idea to use some other tricks to extract interface force as you mentioned.

May be you can have the best from both world justo implementing the basic elementos to ando let the user add them when he needs them.

So less avance users woul contin?e to us? anchors ir piles. It would be conveniente and easier for mist common cases.

More advanced user could use the basic elements to use them in no anticipated ways or to simulate behaviour if structure elementos that have no been yet implementes un a user friendly way.