Control points

[mari.95]

Hi, I have a question. Is there a possibility to create some control point in a solid concrete structure in order to monitor crack's amplitude? Is it necessary to use control points in the software, or not? Thanks in advance.

Mari

[Clarabella]

Dear Mari.95,

You can monitor as many points as you like. You can monitor, for example, strain, stresses, displacements, etc. If you need to monitor crack opening from a continuum model is a bit more complicated because you do not have an actual discontinuity. It would be much easier using discrete or embedded crack approaches or XFEM etc.
Here some interesting literature:
https://hal.archives-ouvertes.fr/hal-01571261/document
https://core.ac.uk/download/pdf/296535499.pdf

An approximated way to measure the crack opening is to measure the crack deformation and multiply it by the critical element's length. It is not difficult to program it in Python with the API interface.

Don't worry. We will probably implement it very soon; it might be useful also for other users.

Regards

[mari.95]

Thanks for the suggestions. But until you implement the code, the only possibility to monitor the crack opening is to use a Phyton script? Is it possible to create a discrete or embedded crack approach or XFEM in Stko?

[Horace Horsecollar]

Dear Mari.95,

as my partner explained you, it is our intention to implement this feature at the earliest. If you have other ideas from literature or experience with other programs, please share your view. As far as we know not many programs have this possibility for continuum models. We use several of them. How do you normally measure the crack width with other programs?

Thank you

[mari.95]

Hi, in my experience I have used Abaqus only, but I'm not an expert user. I know that it is possible to use XFEM approach and when you have an initial crack it is possible to monitor the crack width growth. But in my case of studies I modeled a concrete structure under service load and using a CDP model for concrete I got the results: the damage parameters in tension and compression and then as information about crack I used principal plastic strain (max), but it was just an approximation. In other software like Atena, I know it is possible to insert these monitoring points where investigate the crack width, but I don't know something more, sorry.

[Horace Horsecollar]

You are right, what you said is correct. If you use the concrete damage plasticity or the smeared crack model with Abaqus you cannot measure the crack opening. Today our damage model has the same limitation. Athena uses the approach I suggested in my previous post. It multiplies the crack strain by lc. Shortly we will implement the same approach as Athena so you will be able to track the crack width.

[mari.95]

Thanks a lot for your availability.

[Clarabella]

You are welcome. Keep us posted!