How to apply pretension on bolt and how to represent gap interface?

[wael.alawsey]

Hello there,
As you see ,in the attached pictures, a part of my model, i am trying to model a connection which holds two concrete beams together, maybe i should not post this here because i am dealing with atena static problem type! but maybe you can give me some hints about what to do, so what i am looking for are:
1- how to apply the pretension force on the bolt ? because i have to analyze the connection with multiple values of tightening torque !
2- as you see there is a gap between the washer and the steel plate which is very important for me to study the effect of connection impefection on the whole structure behavior later, so how to model the interface for these distant surfaces? so when i apply the load on the end of the right bolt it will move until it touch the steel plate and transfer load to it!
by the way, there is fixed connection (shared nodes) between the bars on the left and the steel plate, also the same sitiuation for the right bolt and the nut and washer.
best regards.

[escolano]

Sorry, but these questions are completely related to the physics of the simulation, and only an Atena expert could answer them.

Probably to simulate the contact must create for Atena a 'GiD contact separated volume' that is a kind of pseudo-geometric volume that links two 'similar surfaces' that can be in different locations (e.g. moved an rotated) and the mesher will generate a node-to-node related mesh on both surfaces, and elements connecting them. This kind of 1-1 mesh is required for the contact simulation algorithm of several programs, like Atena.

About the prestress force, maybe can be simulated as an extra external force, or a imposed deformation...
In any case must ask Atena, I really never used this code.